Build 9543 - Comments / Problems

2/16/2026 at 10:51 PM

I installed it an hour ago (it's 6:43 am here).

According to my tests, IMAP size limit being handled gracefully seems to be fixed. That's a good thing.

However I did reset the IDS settings that I had removed due to the previous issue and saw some customer IPs being blacklisted.

[2026.02.17] 00:00:38.388 [w.x.y.z] IMAP Attempting to login user: happy@customer.com
[2026.02.17] 00:00:38.388 [w.x.y.z] IMAP Login successful: With user happy@customer.com
[2026.02.17] 00:30:36.411 [w.x.y.z] IMAP Attempting to login user: happy@customer.com
[2026.02.17] 00:30:36.411 [w.x.y.z] IMAP Login successful: With user happy@customer.com
[2026.02.17] 01:36:56.225 [w.x.y.z] IMAP Attempting to login user: happy@customer.com
[2026.02.17] 01:36:56.225 [w.x.y.z] IMAP Login successful: With user happy@customer.com
[2026.02.17] 02:35:07.346 [w.x.y.z] IMAP Attempting to login user: happy@customer.com
[2026.02.17] 02:35:07.346 [w.x.y.z] IMAP Login successful: With user happy@customer.com
[2026.02.17] 03:38:11.383 [w.x.y.z] IMAP Attempting to login user: happy@customer.com
[2026.02.17] 03:38:11.383 [w.x.y.z] IMAP Login successful: With user happy@customer.com
[2026.02.17] 04:29:00.336 [w.x.y.z] IMAP Attempting to login user: happy@customer.com
[2026.02.17] 04:29:00.336 [w.x.y.z] IMAP Login successful: With user happy@customer.com
[2026.02.17] 05:29:13.419 [w.x.y.z] IMAP Attempting to login user: happy@customer.com
[2026.02.17] 05:29:13.419 [w.x.y.z] IMAP Login successful: With user happy@customer.com
[2026.02.17] 06:29:04.474 [w.x.y.z] IMAP Attempting to login user: happy@customer.com
[2026.02.17] 06:29:04.474 [w.x.y.z] IMAP Login successful: With user happy@customer.com
[2026.02.17] 06:36:24.952 DenialOfService [DenialOfService w.x.y.z] Added IP to IDS block list. Duration: 1799,9959026 seconds, Description: Default DoS rule

Ok the customer is successfully logging in with IMAP a couple of time in a few hours time frame but the IP gets blacklisted. I don't get why because it's it's absolutely not connecting 200 times in a 5 minute time frame.... ??

EDIT: Another one just got banned but in Administrative log I see no login attempts, only the ban line: ??? I can't find anywhere else in the log what justifies the ban (looked for the IP in SMTP, IMAP, POP logs)

[2026.02.17] 07:09:02.307 DenialOfService [DenialOfService w.x.y.z] Added IP to IDS block list. Duration: 1799,9980358 seconds, Description: Default DoS rule

EDIT2: Ok I found it in IMAP log, there are plenty of these, maybe an SSL issue...

[2026.02.17] 06:34:46.298 [w.x.y.z][20485989] Connection initiated

[2026.02.17] 06:34:46.301 [w.x.y.z][62933395] Connection initiated

[2026.02.17] 06:34:46.303 [w.x.y.z][17744703] Connection initiated

[2026.02.17] 06:34:46.305 [w.x.y.z][49934855] Connection initiated

[2026.02.17] 06:34:46.307 [w.x.y.z][48795366] Connection initiated

[2026.02.17] 06:34:46.309 [w.x.y.z][52990363] Connection initiated

EDIT3: Other than that it seems there is way more DDoS IDS rule triggered comparing to bogus build 9540... I'm maybe a bit too sensible, watching closely the server after the issues we went through yesterday...

Sébastien Riccio System & Network Admin https://swisscenter.com

Sébastien Riccio Replied

2/16/2026 at 10:55 PM

Also there is quite some IPs for which SM is not able to resolve the country, but if I test it with maxmind, it returns data:

Sébastien Riccio System & Network Admin https://swisscenter.com

B

Bruce Replied

2/17/2026 at 12:47 AM

I have my DoS rule set to 500 within 5 minutes and I'm still seeing users being blocked. This didn't occur before. Looking in the logs, I can see activity, but nothing that would warrant blocking them.

I have deleted the DoS again to stop any more false triggers.

J

J. LaDow Replied

2/17/2026 at 1:18 AM

Back when we first started using SmarterMail, we had issues with the default DoS rule - and set ours to some ridiculous amount - and so far it's held. I think ours is set to like 5k over 10 minutes. Will have more info after we push the update to see if behavior changes on our end. I would be looking for disconnect errors anywhere that might be causing the client to reconnect continually as well.

On top of all that - IMAP is a notoriously heavy protocol and clients like Outlook and iOS have buggy implementations to begin with. With ST tightening "loose ends" - we're starting to see where things weren't quite implemented in past builds (like IP restrictions on a user account being applied to API access) - and issues like IMAP "attachment" handling being fixed to respect "file size limits" that are actually defined on the server - etc.

MailEnable survivor / convert --

Webio Replied

2/17/2026 at 2:05 AM

If someone is using SmarterMail as incoming gateway with Web Service verification then please check main SmarterMail instance IIS logs for request 500 errors when performing POST to main gateway from incoming gateways for web service verification for incoming emails:

2026-02-17 08:43:02 MAINSMIP POST /Services/svcProductInfo.asmx X-ARR-CACHE-HIT=0&X-ARR-LOG-ID=f3eb4f8c-b437-47a2-b14f-cee8bf1c3afc&SERVER-STATUS=500 443 - GATEWAYIP - - 500 0 0 17

After update to 9540 and also 9543 I've started to get 500 errors for POST requests from incoming gateways in IIS main SM instance log. This is causing issues with "550 Relay is not allowed" errors for mailboxes created AFTER recent update (it looks like incoming gateways keep some kind of cache).

I've added gateways IPs to restricted IPs, I've even disabled restricted IP for administrator account which is being used by incoming gateways to perform web service requests. Nothing helped.

EDIT: So far it looks like switching from WebService to SMTP User Verification allowed to solve this problem.

t

terry fairbrother Replied

2/17/2026 at 2:34 AM

I have a problem logging into the free version. I normally sign in as XYZ-admin and it goes into the full manage pages, however it's now saying

so when I sign in with XYZ-admin@example.com, it's just the webmail style logon with only the subset of management tools

I had no issues on previous versions

The paid for version I also manage signs in without the domain and is fine, just the free version

EDIT

I extracted the administrators.json file from a backup, copied the data across and after a little poking around, i'm back in and upgraded fine. The only difference I can see between Sundays backup and today was I added a user as a domain administrator.

YS Tech Replied

2/17/2026 at 5:31 AM

Ok, it would seem that I need to hold off for another update before i update again :o(

Derek Curtis Replied

2/17/2026 at 9:09 AM

Employee Post

@Sebastien, regarding that client and the DoS block, it kind of looks like the client is stuck, so it's spamming new requests over and over as the entries are all within milliseconds of each other. And preventing that is kind of the purpose of the IDS rule.

We've done some testing this morning and can't replicate any legitimate traffic blocks, but alternative traffic IS being blocked as expected.

Derek Curtis CCO SmarterTools Inc. www.smartertools.com

D

Douglas Foster Replied

2/17/2026 at 12:49 PM

@WebIO

Yes, there is a cache on recently-created accounts. From the help

Note: SmarterMail uses a cache of the domains and users on a server, so if there are any changes (e.g., additions, modifications like enabling/disabling users or domains, or deletions) these changes may not be reflected for up to 10 minutes until the cache is refreshed.

rick Replied

2/17/2026 at 1:02 PM

Just dealt with a MacMail customer using IMAP. Activity window saying Moving Msgs 1 of 49, just hanging but bombarding SM with connections over and over tripping the DoS rule.

Several more people claiming they cannot get IMAP mail on Outlook but can get on phone.

Still running 9540, not sure if upgrading with fix this and/or break something else :-(

J

J. LaDow Replied

2/17/2026 at 1:08 PM

9540 has a broken IMAP implementation. 9543 fixes it.

If you have an Outlook user that is still having trouble after the upgrade and restart, they may need to recreate their Outlook profile to restore mail-flow. Outlook caches things and can't recover sometimes when there's server problems - so even after you upgrade, the client may "DoS" the server because the stuck messages are corrupted. Deleting the profile (or affected account and re-adding it) usually fixes it.

MailEnable survivor / convert --

f

fatih.gulsuyu Replied

2/18/2026 at 8:26 AM

Unfortunately, even for a few users where recreating the Outlook profile initially appeared to resolve the issue, the problems returned after about 4–5 hours. They started experiencing synchronization errors again, along with slowness and occasional freezing in Outlook. Because of that, it doesn’t seem to be a fully reliable or permanent fix in our case.

It looks like the profile reset may only provide temporary relief rather than addressing the underlying cause.

J

J. LaDow Replied

2/18/2026 at 8:39 AM

You will probably need to re-visit your support ticket if you've already upgraded to latest version and are still seeing issues after resetting the profile and re-syncing on the SmarterMail end.

MailEnable survivor / convert --

Nageswara Rao Anumolu Replied

2/19/2026 at 2:40 AM

My server stopped responding with spinning wheel from today morning. Is there anyone that can help to troubleshoot?

L

Luk Replied

2/19/2026 at 5:24 AM

@fatih.gulsuyu Users most likely using diacritical marks in folder names. After updating Smartermail to 9542, many of our users are experiencing similar issues, and removing the diacritical marks solves the problem. I hope Smartertools will resove this in another build.

G

George Replied

2/19/2026 at 8:29 AM

According to my findings, the problem affects MS Outlook users who have localized folder names in their profiles. All those who had synchronization problems had localized names. Those who had English names in their profiles did not report any problems.

We fixed most of them and converted the folder names to English. Synchronization now works without any problems. However, we do not want to go through this nightmare again. I will carefully consider the next upgrade. I will first upgrade the test server and verify that it works as expected.

Derek Curtis Replied

2/19/2026 at 9:56 AM

Employee Post

Edited with some more specifics: As mentioned in another thread where George posted, after some troubleshooting of our own, we were able to find a very specific scenario affecting IMAP accounts in Outlook, and folder names with some specific non-ASCII characters. Incidentally, eM Client and Thunderbird appear to work just fine, so it appears it's limited to Outlook. We've seen very few tickets on this, some from people here in the Community, but it's an issue so we'll get a fix out for it today.

Derek Curtis CCO SmarterTools Inc. www.smartertools.com

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