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Outlook MAPI connections breaking
Problem reported by Matthew Titley - 10/1/2025 at 5:51 AM
Known
Has anyone else seen an uptick in broken MAPI sync connections lately? I've noticed over the past month or so an increase in support calls regarding broken Outlook connections. Customers have reported the classic "Your mailbox has been temporarily moved on Microsoft Exchange server. A temporary mailbox exists..." yadda yadda. As far as I've seen the only fix is to recreate the profile.

What I've been doing is adding the reg key ExcludeExplicitO365Endpoint 1 to the Outlook autodiscover hive, during a remote support session, and then recreating the Outlook profile. It works as a solution but I'm a bit mystified as to why this is happening more frequently lately. It's a fairly quick fix except for the time it takes for the customer's account to fully resync. I haven't upgraded since build 9229 in April. Most users are on either Outlook 2019 or 2021. I suspect it has something to do with Microsoft accounts somehow confusing Outlook but I don't know for sure. Anyway, just curious if this is a localized occurrence or if others have been seeing it also.

Matt
Derek Curtis Replied
10/1/2025 at 6:55 AM
Employee Post
We've not seen an uptick in tickets on this, as far as I know, but I'm curious to know if others are seeing it as well. 
Derek Curtis COO SmarterTools Inc. www.smartertools.com
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Douglas Foster Replied
10/1/2025 at 12:03 PM
I ran into problems four years ago, and solved them by setting two registry keys:
 "ExcludeExplicitO365Endpoint"=dword:00000001
 "ExcludeScpLookup"=dword:00000001

When those are not disabled, it is possible for Office365 to accept the user despite the unauthenticated connection.   Messages sent from the unauthenticated account are accepted and delivered using an SMTP Mail From address of the form  outlook_digitstring@outlook.com, which of course is useless for replies.   That incident happened with a user on a Hosted Exchange domain at a third-party hosting service, not with SmarterMail.   I am guessing that something similar is happening to your damaged users.   
Michael Replied
10/2/2025 at 7:58 AM
We just had a case of this. One user on one domain. Deleted outlook profile and resync.but interesting about the timing. 
Eric Tykwinski Replied
10/2/2025 at 9:04 AM
Matt,

There is a bug just announced about MAPI breaking on Office versions:

I've personally seen this as well this past week with several clients, as well as the temporary mailbox issue and think they may be related.
Michael Replied
10/2/2025 at 2:35 PM
Very interesting. 
Seph Parshall Replied
10/16/2025 at 12:50 AM
Where are those Registry keys located?
I'm having the same problem and it's growing
Eric Tykwinski Replied
10/16/2025 at 7:12 AM
Seph,

Typically, it's this in PowerShell:
Set-ItemProperty -Path “HKCU:\Software\Microsoft\Office\16.0\Outlook\AutoDiscover” -Name ‘ExcludeExplicitO365Endpoint’ -Value 1 -Type DWORD –Force
Version 16.0, might be different, you'll have to look.  ExcludeScpLookup is for a local AD lookup, which you may need, but I usually don't.
Matthew Titley Replied
10/16/2025 at 10:54 AM
@Douglas Foster, I, too, would occasionally have to tackle the issue by using the reg keys but it used to be rare. However, I've noticed this issue becoming far more frequent. Just in the past few weeks I've had a number of support calls where Outlook was losing it's sync status and the only solution (that I've found to work) is to add the ExcludeExplicitO365Endpoint 1 reg key and then recreate the profile.

As I'm sure others have read in IT news, Microsoft is working hard to close the various avenues of Windows access (local or AD) without Microsoft accounts. It's not much of a stretch to believe that Microsoft wants all Outlook accounts to work only through O365. Regardless, this issue will probably become more prevalent to non-O365 hosted email users wanting to use Outlook and MAPI with SmarterMail. It doesn't look like there is anything that ST can do about it, though.

The odd thing is that there is a randomness to it. I can setup a user with Outlook MAPI with no error sometimes. Down the road a few weeks or months it might break. Or, sometimes, I simply cannot create a new Outlook MAPI account without adding the reg key. I'm fairly certain that the common denominator is the user having a Microsoft account address that matches their Smartermail email address.

Matt
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Douglas Foster Replied
10/16/2025 at 1:28 PM
It the O365 option is not forced off, I would worry that Microsoft might create a successful connection with itself in the middle.   Then that connection might or might not work, depending on timing problems and the quality of there implementation.   Of course, it would also be a problem because they would have access to your credentials as well as  your email content.

Several  years ago I tested Outlook Mobile.  The connection worked, but messages were delayed by minutes.
Later, I fought autodiscover performance and reliability problems, and found that the registry changes made the application startup much faster and the connection became reliable.
Matthew Titley Replied
10/21/2025 at 9:50 AM
Two more yesterday, and four more today. Modify reg, create new profile, problem solved, wash, rinse, repeat. The fact that it seems to be happening far more frequently with my hosted customers (based upon the paucity of others reporting the same issue) is worrisome. Guess I'll open a ticket on the issue, but I have my doubts that there is any server configuration or DNS record issue seeing how this has spiked just recently.
Tim Uzzanti Replied
10/21/2025 at 11:35 AM
Employee Post Marked As Resolution
No reason to open a ticket on this.  Nothing we can do; it's just Microsoft boinking Outlook with updates and trying to run things through their servers even though your mail is hosted on different platforms.  Microsoft is not a good actor these days!
Tim Uzzanti CEO SmarterTools Inc. www.smartertools.com
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Mike Mulhern Replied
10/21/2025 at 12:15 PM
Had my first instance of this today.
Matthew Titley Replied
10/21/2025 at 12:36 PM
Hi Tim,

Thanks for the response; it's much appreciated! Seeing how, as a community, we're all in the same boat regarding MAPI and Outlook, it's hard to know what to do other than address the issue ad hoc as customers report problems. That being said, does anyone at ST know exactly what change or update Microsoft has either made or pushed which has resulted in this surge in MAPI problems? The reason I ask is that, for example, if I have one customer with ~40 Outlook 2021/2024 MAPI accounts, to date "only" ~20 have broken and I see no configuration differences among the fleet of devices. 

Is it a specific Windows Update KB patch or something else, such as some change occurring on Microsoft account login? If ST hasn't received any clear information from Microsoft, I would not be surprised in the least, unfortunately. I can only imagine how irritated you must be over this.

Thanks,

Matt
Tim Uzzanti Replied
10/21/2025 at 1:28 PM
Employee Post
We have no idea. We love finding workarounds, but we can’t see anything that would help alleviate the issues. It doesn’t matter whether you’re using SmarterMail, Exchange, or even Office 365; Outlook is truly falling apart at the seams with all the changes Microsoft is making to route more and more traffic through their own servers, whether for autodiscover or actual mail data.

Another issue we’re seeing frequently that is also affecting Office 365 users is:

Almost 50% of our support tickets right now are Outlook-related. It really sucks that we can’t do more to help.

We’ve moved all of SmarterTools off Microsoft products. This comes from someone who built one of the largest Windows hosting companies back in the day — and developed Mail, Stats, and Track products for ISP and hosting companies running Windows.  

We have been using .NET since its inception and during their initial BETA release, we were working very closely with Microsoft on issues.  Now, we just hope they don't boink .NET like they have everything else.  We don’t use Azure or Office365 because they’re kind of awful and getting support is a test of patience, with some incidents going for months. 

Microsoft is a very different company now, and it’s disappointing.
Tim Uzzanti CEO SmarterTools Inc. www.smartertools.com
Oliver Replied
10/21/2025 at 2:08 PM
@Tim, I completely agree with you. Microsoft is just so frustrating!
Seph Parshall Replied
10/21/2025 at 5:23 PM
This issue that Tim links to [on Microsoft website] was my first indicator of a problem. After a while I couldn't re-connect Outlook to the email account on SmarterMail. The only thing that fixed it was the Registry hack. This is only affecting my customers that login to a Microsoft account to activate MS Office. Logging into MS Office in any Office product [Word, Excel, Outlook] for activation should be a red flag for anyone reading this thread. That is the common denominator from my experiences.
Thanks everyone!
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Emory Kempf Replied
10/22/2025 at 9:40 AM
How about you modernize the webmail interface to a point where users can use it as their daily driver? We currently advise users to use webmail as a workaround, but most users find it too cumbersome to use full time. I can provide more details if you are interested improving webmail.

I currently use Spark and enjoy it a lot.


Tim Uzzanti Replied
10/22/2025 at 12:53 PM
Employee Post
We are re-doing Webmail in React (currently Angular).  The new SmarterMail High Availability Hub interface was built on React and is the foundation of the new Webmail moving forward.  It is a major project, Webmail is huge!  We are continuing to improve what we have, building it out, and delivering new features, all while working on the new Webmail simultaneously.  I don’t want to sidetrack this thread discussing more about Webmail and can discuss it more in the future in another thread.  Appreciate the feedback and we will definitely be getting suggestions and guidance from customers as we move forward.   
Tim Uzzanti CEO SmarterTools Inc. www.smartertools.com
I know its a big thing... can tyou replicate the look of outlook in webmail?

Then everybody would be ecstatic :)
Matt Petty Replied
10/23/2025 at 9:13 AM
Employee Post
"How does this look in Outlook/eM Client/Exchange/Google (sometimes)" comes up *often* in our design discussions especially for things like terminology. So hopefully there should already be a lot of cross over in that regard but we overall have a design that we like to stick to across sysadmin <--> users and even at times our other products. From cards, tables, warning messages in card, the color and order of buttons in all the dialogs, etc we try to be very consistent.

For example we did this cross-referencing when we were implementing the delay/schedule message sending, which should be coming down the pipeline very soon.
Matt Petty Senior Software Developer SmarterTools Inc. www.smartertools.com
I run this on every user account setup

reg delete HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover\RedirectServers /f
reg add HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover\RedirectServers /f
reg add HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\setup /t REG_DWORD /v DisableOffice365SimplifiedAccountCreation /d 1 /f
reg add HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover /t REG_DWORD /v ExcludeExplicitO365Endpoint /d 1 /f
reg add HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover /t REG_DWORD /v ExcludeHttpRedirect /d 1 /f
reg add HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover /t REG_DWORD /v ExcludeHttpsRootDomain /d 1 /f
reg add HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover /t REG_DWORD /v ExcludeScpLookup /d 1 /f
reg add HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover\RedirectServers /t REG_DWORD /v yourmailserver.com /d 1 /f

Then youre rid of most mail problems right away. 
Tim Uzzanti Replied
10/27/2025 at 6:45 AM
Employee Post
Brian,

Appreciate you sending over what you're using.  You have additional keys there than what we normally propose and I'm going to have someone looking into them and see if they will help with any of the current issues. It's shame this is where we are at with Outlook.  
Tim Uzzanti CEO SmarterTools Inc. www.smartertools.com
Matthew Titley Replied
10/27/2025 at 6:53 AM
Hello, Brian.

Thanks for this. Currently, I only do the ExcludeExplicitO365Endpoint and that's only recently since this problem has cropped up in a seriously substantive way. I still have a slew of customers setup using MAPI whom haven't experienced the connection failure. I guess I should create a deployment script including all those other reg entries.

General question for all. Does anyone have confidence or evidence that making these registry changes after profile creation will "inoculate" an Outlook profile from this problem? I ask in that approximately 60% of our customers haven't had the issue yet... It's like the sword of Damocles hanging over them... and me... lol.

Matt
Tim Uzzanti Replied
10/27/2025 at 7:22 AM
Employee Post
Matthew,

It really does seem random why some Outlook accounts have issues while others don’t. That’s one of the many reasons it’s so difficult to pinpoint what’s going on along with certain issues being related to on-premise mail servers including SmarterMail and Exchange but some affecting Office365 as well.  

We’re going to test some of these additional registry keys and then work with customers to see if they lead to any improvements before we update our documentation.

Another challenge with Outlook is that once it goes bad, making registry changes usually doesn’t fix the problem. Those changes are more preventative than corrective. In most cases, you’ll need to re-add the accounts and then wait to see if the issues reappear.

Just wanted to give you an idea of how we’re approaching this.

As I mentioned in a previous post, Outlook-related problems now make up almost 50% of the tickets coming into our help desk — and unfortunately, there’s not much we can do until Microsoft makes changes or we discover some combination of “magic” that helps.

We really appreciate customers sharing any information or findings as we all work together to find solutions.
Tim Uzzanti CEO SmarterTools Inc. www.smartertools.com
Tim Uzzanti Replied
10/27/2025 at 7:22 AM
Employee Post
BTW, I have changed this thread to Known since nothing is resolved and it's an ongoing battle.  Hopefully that helps encourage others to participate and monitor.  
Tim Uzzanti CEO SmarterTools Inc. www.smartertools.com
Andrew Barker Replied
10/27/2025 at 5:10 PM
Employee Post
We're still reviewing the registry settings for Outlook, but I wanted to share what I've found here so far. Most of this information comes from a Microsoft webpage about autodiscover behavior in Office 2016. I've added the link for that page at the bottom of this post.

Based on the information provided by Microsoft, Outlook uses the below steps for autodiscover. If Outlook successfully retrieves autodiscover information at any point in this process, it skips the remaining steps.

  1. Check for restart scenarios. This is a shortcut that seems to only apply when configuring a new account in Outlook. To help configure the account, Outlook will retrieve and cache the needed autodiscover information. It then restarts Outlook, and will use the recently cached information instead of doing a new autodiscover lookup.
  2. Check for local data preference. If the machine has the PreferLocalXml policy enabled, Outlook will search for an XML autodiscover file on the local machine. The location of that file is specified by a string value in the HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover registry key.
  3. Check for Last Known Good data. If Outlook has previously loaded the account and cached the autodiscover information, it will use it for this step. However, Outlook will only do this for the primary account in a profile.
  4. Check for Office 365 priority. At this stage, Outlook uses an undefined set of heuristics to determine if the account references an O365 user. If it "determines confidently" that the account refers to an O365 user, then it will utilize known O365 endpoints to get autodiscover information.
  5. Check for Service Connection Point (SCP) data. If the machine is joined to a domain, Outlook will perform an LDAP query to get SCP data. If the query returns any SCP data, Outlook will attempt an autodiscover request against every provided URL.
  6. Check root domain. Using the provided account information, Outlook builds a basic URL like https://<domain>/autodiscover/autodiscover.xml and attempts an autodiscover request against that URL.
  7. Check autodiscover domain. Using the provided account information, Outlook builds a basic URL like https://autodiscover.<domain>/autodiscover/autodiscover.xml and attempts an autodiscover request against that URL.
  8. Check for local data. If step 2 was skipped because the PreferLocalXml policy was disabled, Outlook performs that check here.
  9. Check for HTTP redirects. Using the HTTP version of the URL from step 7, Outlook performs an autodiscover query, if an autodiscover response is returned, Outlook ignores it because it was retrieved in an insecure manner. If the response provides a redirect, Outlook follows the redirect to retrieve autodiscover information.
  10. Check for SRV data. Outlook performs a DNS lookup for _autodiscover._tcp.<domain>. If any results are found, Outlook uses the first one that specifies HTTPS to do an autodiscover query.
  11. Check for O365. Outlook uses an undefined set of relaxed heuristics to determine if there is a chance that the account might be available on O365. If it determines that the user might be on O365, it will try the same endpoints as in step 4.
Most of these steps can be controlled by various registry settings in one of two registry keys. The page I referenced earlier suggests using the key HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\AutoDiscover to apply these settings as policy such as with Group Policy, or using HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover for non-policy applications. Set the following DWORD values in one of those keys with data set to 1 to trigger the associated behavior:

  • PreferLocalXML affects step 2. Needs to have a string value next to it to indicate where to look. The name for that value should be the referenced domain and the data field should specify where the autodiscover XML is located.
  • ExcludeLastKnownGoodURL skips step 3.
  • ExcludeExplicitO365Endpoint skips steps 4 and 11.
  • ExcludeScpLookup skips step 5.
  • ExcludeHttpsRootDomain skips step 6.
  • ExcludeHttpsAutoDiscoverDomain skips step 7.
  • ExcludeHttpRedirect skips step 9.
  • ExcludeSrvRecord skips step 10.
Based on what others have reported in this thread, as well as our own findings, it seems that using ExcludeExplicitO365Endpoint to skip steps 4 and 11 has the most impact, though the other values may be useful depending on your specific setup.

The other registry keys that Brian mentioned, such as RedirectServers and DisableOffice365SimplifiedAccountCreation have no impact on the autodiscover process and seem designed to alter the user's experience during account setup. The first allows you to prevent the confirmation dialog associated with accepting autodiscover settings from specific servers, and the second reverts the account creation wizard to the format used in older versions of Outlook.
Andrew Barker Senior Software Developer SmarterTools Inc. www.smartertools.com
Matthew Titley Replied
10/28/2025 at 7:07 AM
FWIW. Yesterday on one of my laptops, Outlook 2024 suddenly started nagging me for my Microsoft account password. Outlook stopped syncing with my SM server until I entered it, but I didn't get the dreaded "Your mailbox has been temporarily moved" error. I have no need for the MS account to be connected to Outlook. So, I closed Outlook, opened regedit, added the ExcludeExplicitO365Endpoint key (totally from memory btw because I've been doing it so frequently lately!), restarted Outlook and the MS account nag has gone away. Hopefully, that alone prevents future problems...
Andrew Barker Replied
10/28/2025 at 8:34 AM
Employee Post
Here are some more registry settings I found that are related to Outlook setup. I don't expect them to improve Outlook's ability to connect to SmarterMail, but they could be useful for troubleshooting.

Key: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover
DWORD: EnableOffice365ConfigService
Data: A value of 1 modifies steps 4 and 11 of the autodiscover process to use the Office 365 Configuration Service instead of the standard O365 autodiscover endpoints.
Notes: This value is intended to improve the setup experience for Office 365 accounts. I recommend against using this key when connecting to SmarterMail.

Key: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover
DWORD: Timeout
Data: A value between 10 and 120, default is 25.
Notes: This specifies the timeout Outlook will use for autodiscover requests in seconds. This could be useful if it appears that the autodiscover process is failing due to delayed responses.

Key: HKEY_CURRENT_USER\Software\Microsoft\Exchange
DWORD: MapiHttpDisabled
Data: A value of 1 disables the MAPI over HTTP protocol.
Notes: Do not use this with accounts that utilize MAPI.

Key: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover
DWORD: ShowCertErrors
Data: A value of 1 causes Outlook show select certificate errors to the end user, giving them an opportunity to accept the certificate with the errors.
Notes: This may be useful for helping to diagnose certificate related issues, but is not generally a good idea. Enabling this permits users to ignore the following certificate errors:
  • Problems with the date on the certificate.
  • Problems with the certificate's common name.
  • Problems with the certificate authority.
Andrew Barker Senior Software Developer SmarterTools Inc. www.smartertools.com
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Bert Garrett-Tuck Replied
10/28/2025 at 10:34 PM
Now getting a handful of these lately.
Will try the registry hacks.
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Romeo Marra Replied
10/30/2025 at 10:28 AM
Is there an alternative to outlook that uses activesync or EWS in a similar way that doesn't have these problems?
Derek Curtis Replied
10/30/2025 at 10:33 AM
Employee Post
Re-reading my original reply I realized I'm not really offering a good comparison between Outlook and eM Client, and why I feel eM Client is a good alternative. So, allow me to correct that:

First off, remember we do offer a free license of eM Client with 3 activations for any SmarterMail install. These are accessible from the Marketplace. If you're having trouble finding them, shoot us a ticket to sales@smartertools.com and we can help you figure things out.

Next, eM Client ties into SmarterMail via EWS, sure, which is essentially the MAPI protocol for non-Outlook clients. You get delegation, collaboration, etc. using it. And eM Client offers encryption levels when you set up your account, which is nice. 

Next, we work with eM Client very closely. We've worked together to integrate SmarterMail into eM Client, and vice versa. For example, you can use SmarterMail's Online Meetings as a meeting location when setting up appointments in eM Client. In addition, setting up a SmarterMail account in eM Client is a BREEZE. You add in your credentials and it's all set up automatically: email, calendars, contacts, tasks, notes...and even live chat! 

Finally, I'll touch on the partnership again: we have a very strong and reliable two-way relationship with eM Client. If we have an issue, we have a few people to contact about it, not the least of which is their CEO. (Who, by the way, has visited us a few different times over the years.) They can do the same with us: if they have a SmarterMail customer having issues, they'll reach out to us and we'll work together on a resolution. Our companies are in sync with how things work, how things SHOULD work, and how to go about resolving issues, growing our products, and improving the user experience. Therefore, it's a very easy and productive relationship. 

Oh, I forgot to mention their mobile client: they just released it a few months ago, and are working on it constantly. Extremely nice and is almost an exact mirror of their desktop client. It uses EWS (EDIT: I forgot and initially put EAS) as well, so EWS is all you need for both their desktop and mobile clients!

Of course, both desktop and mobile clients work with POP/IMAP as well, but using EWS and EAS offers the greatest amount of Outlook-like functionality across platforms.

So...eM Client is my recommendation as a replacement for Outlook as it is the Microsoft Outlook alternative, just as SmarterMail is the Microsoft Exchange alternative. 
Derek Curtis COO SmarterTools Inc. www.smartertools.com
Matthew Titley Replied
10/30/2025 at 11:58 AM
Thanks, Derek, very much for your thoughts. I like EM Client and use it in addition to Outlook. The more difficult obstacle is convincing customers of the advantages of this. Even if I can convince them to use a different email client for Windows, convincing them to drop Word and Excel for LibreOffice (or other) would be a challenge. I'm sure the typical response would be "We want to use Office, but you say don't use Outlook and buy an additional email client that isn't really integrated with Office?" I'm sure that my rationale for going down this path would be questioned. Nevertheless, it's a solution for getting out of the Microsoft world (somewhat... we'd still be paying for MAPI/EWS/EAS which eventually goes to MSFT)

I hate to muddy the waters of this thread which is primarily about Outlook/MAPI sync issues... Thanks, again!

Matt

Oh, and to recap for all, ExcludeExplicitO365Endpoint seems to be the most important reg key to fix this.
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Emory Kempf Replied
10/30/2025 at 12:38 PM
eM Client is functionally the best alternative. However, most of our users (including myself) find the UI unpleasant to use (as they do with the SM web interface). I just had someone come in the office this morning with Outlook issues to report, and when asked why they're not using the eM Client software we set up some time ago, the answer was that it's not nice to use it. That being said, some people get along with it just fine.

If you don't need contacts, I would suggest Spark. Just like em Client, not all people will like the user interface. I find it modern and appealing. By default it will attempt to connect via imap, but if you hit the back arrow during the imap setup, you can choose exchange. Search google for spark for windows to find it.

Edit: Can staff split this to a new topic? Side note {it would be cool if SM could switch to an actual forum software like discourse 😁}
There is no plausible alternative to Microsoft Office is you are a customer and wants what everyone else got...

And they dont wanna be a guinea pig....

Thats our main issue. If we introduce 3rd party alternatives then its us that gets the bullshit if nothing works and we recommended that they went down that route....
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Romeo Marra Replied
10/31/2025 at 6:16 AM
Perhaps SmarterTools should supply an executable that fixes all the registry entries for all versions of problematic outlook - updated regularly with whatever fixes are necessary.  This way, we can simply point our customers to the link - they execute on their PC and problem solved, without having to explain to them how to make Registry changes.  We pitch this solution to our customers as an alternative to M365 and we can't continue to use the "Microsoft will do what they want" excuse. At some point, they'll get fed up and simply move.
That would be an excellent solution.
Richard Laliberte Replied
10/31/2025 at 8:08 AM
This would be a good option for some of our clients, but we do have many others that this is a no-go for "security" reasons. We've been pushing more clients to webmail instead of desktop mail system. They seem to be more in favor of this option then installing something different like Thunderbird and such. I remember reading that there was new development, including a new UI for the webmail, maybe a lot more focus should be placed there to get that out the door faster? Then all we really need is an installer that places an icon on a users desktop that opens webmail and logs them in automatically with locally stored credential keys perhaps?

if SM goes this route, we  can tell clients forget Outlook, it's junk, download your customized installer from your webmail login, install it and use that going forward.
Matthew Titley Replied
10/31/2025 at 12:48 PM
You know... creating a package of registry changes which would prevent this problem is a good idea, from my perspective. If anyone has experience with Kerio, they have a Kerio Outlook Connector client which, although it may or may not install other proprietary software, in essence results in the same outcome: making Outlook communicate with the mail server for MAPI support. One problem, I suppose, is for SM to be confident that all these registry mods are a reliable and durable solution. It's a bit of a hack, I guess, as it shouldn't be necessary but it's where we are.
I switched from MAil.enable for that exact reason... no middleware. Native MAPI integration.

If SM goes down that path I need to go somewhere else. Typoe in your email and your password and be done...

Thats the way to go.
Matthew Titley Replied
10/31/2025 at 1:04 PM
@Brian, I created a script including all of those registry changes you posted here last week (some of those I've tinkered with in the past) and ran it on a client's PC successfully. Looks good. Thanks for that!
Youre welcome mate :)
Tim Uzzanti Replied
11/1/2025 at 7:04 PM
Employee Post
Mathew,

The Outlook plugin modules you’re referring to for Kerio and MailEnable use proprietary software that each company wrote and must be installed on every Outlook client. It is another thing to manage. These plugins simulate MAPI by using IMAP, SMTP and DAV in the background, which are not secure and only offer a fraction of what MAPI or EWS provides. The plugin architecture in Outlook has been end-of-life for quite some time, is extremely finicky, and wouldn’t resolve some of the issues we’re all seeing with Outlook today.

Most mail providers are actively working to eliminate legacy protocols like POP and IMAP for security reasons, which will make these connectors even more problematic moving forward. The new Outlook also no longer supports these plugins.

Trying to throw out some facts — everything is getting so complicated these days, and we’re trying to stay as transparent as informative as possible to help customers out. 

When we set out to better integrate Outlook with SmarterMail years ago, our customers made it clear they wouldn’t accept third-party plugins in Outlook. We work with governments and corporations worldwide, and our investment in true MAPI support has proven well worth the effort. Of course, some of these concerns may not apply to your particular environment, which we completely understand.

That said, Microsoft can’t abandon on-premise Exchange servers indefinitely with the new Outlook, nor can they require routing through their backend servers without violating GDPR and other emerging global regulations.

Hope this helps!
Tim Uzzanti CEO SmarterTools Inc. www.smartertools.com
Cris Mead Replied
11/5/2025 at 5:08 AM
Best thread in this community, Thank you to all contributors, this helped immensely 
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