SmarterMail Server on Windows 10 - POP3 retrieval often stops working
Question asked by Stefan Mössner - November 16, 2016 at 7:10 AM
Answered
Hello all,
 
after a hardware crash and bare metal recovery on new hardware of my Windows 2012 R2 Server which hosts my SmarterMail Free Edition I'm not able to reactivate my Windows licence. So I decided to do a workaround by using SmarterMail on a Windows 10 Professional "Server". It runs really great - even with the own web server because I wasn't able to get SmarterMail running with IIS on Windows 10.
 
But there seems to be an issue for retrieving mails by POP3 from my mail provider. Nearly all 3 days I have to restart the SmarterMail service to get the POP3 retrieval working again. In the past I didn't had this issue. I'm running SmarterMail 15.4.6151. I'm running a hourly backup task of the mail data by FreeFileSync (see freefilesync.org) On my old system I used PersonalBackup once a day.
 
Can someone confirm this issue? Does it raise because of Windows 10? Or could it be related to the backup procedure?
 
Thank You.

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Bruce Barnes Replied
The SmarterMail wev service is,designed for,installation and, setup only. It does not support TLS encryption, and,does not support the most recent Windows pop protocols. 15.5 us,the,most recent version, and resolves many of the Outlook hssues, but, again, only wheb running bder IIS.
Bruce Barnes
ChicagoNetTech Inc
brucecnt@comcast.net

Phonr: (773) 491-9019
Phone: (224) 444-0169

E-Mail and DNS Security Specialist
Network Security Specialist

Customer Service Portal: https://portal.chicagonettech.com
Website: https://www.ChicagoNetTech.com
Security Blog: http://networkbastion.blogspot.com/

Web and E-Mail Hosting, E-Mail Security and Consulting
0
I can't follow your answer. I don't have an issue with the SmarterMail Web Server. I have an issue with the POP3 retrieval which is under control of the SmarterMail service.

And what do you mean with 15.5? Is this the comming release? This release isn't available to download.
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Employee Replied
Employee Post
Another potential cause of this behavior is the built-in maximum connection limit in non-server versions of Windows. Typically we recommend deploying SmarterTools products in Server 2008 R2 at least, but recommend Windows 2012 Server. There may be a way to disable the concurrent connection limits in Windows 10 Professional, but I'd recommend testing these instructions in a non-production environment first.
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For my understanding the connection limit of a Windows client OS is regarding incomming connections, isn't it? And the POP3 retrieval is an outgoing connection to my mail provider.

For more clarification: I don't use any mail client software to work with SmarterMail. I'm only using the web UI, which is really great. In my home network there aren't many concurrent connections.

While the POP3 retrieval isn't working all other connections are available: SMTP from internal devices to SmarterMail and from SmarterMail to my mail Provider and the access to the web UI.

I haven't found a detailed POP log. There's only a log file regarding POP when the SmarterMail service is restarted. So I'm not able to troubleshot this issue.
 
After restarting the SmarterMail service yesterday in the evening, POP3 retrieval was working again until today in the morning. This time the working period was very short.
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User Replied
Hello Stefan, I believe the concurrent connection limit is inbound/outbound included, and not limited to just inbound connections but I am not certain. I think your best bet will be deploying on a server operating system to ensure connection limits are not preventing proper functionality. If you continue to experience these issues on a server OS, please open a support ticket so we can investigate this further. Thanks for your time!
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As I wrote I didn't had this issue with Windows 2012 R2 Server in the past. But I don't get the licence reactivated any more after the bare metal restore on a new machine. So my licence seems to be invalid now. I'm a private user and I don't want to buy a new server licence now. So I decided to switch to Windows 10.
 
Windows 10 allows a limit of 20 (both technical and legal) on incoming TCP connections. So anything, network shares, web, email... whatever you decide to host on the desktop is limited to only twenty open connections at a time. That's twenty connections, not twenty services. You could have services that use more than one connection at a time and use these up faster than one to one.
 
So the POP3 retrieval shouldn't be limited by this maximum of connections because it's an outgoing connection. And as I wrote the web mail access and the mail send via SMTP (also an outgoing connection) are working fine even if POP3 doesn't work.
 
Is there a possibility to run a debug log for the POP3 retrieval? Maybe there's a hint to solve this issue.
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Now I found the setting for a detailed log of SmarterMail. And I will monitor the TCP connections when POP3 retrieval won't work anymore. So hopefully there will be a hint for further troubleshooting.
 
Today I saw that the POP3s connection (TCP port 995) was still active. It didn't terminate. But after closing this connection SmarterMail still wasn't able to do POP3 retrievals. I had to restart the SmarterMail Service and then the retrieval was working again.
 
I have to say that the Windows 10 machine is only running SmarterMail and FreeFileSync for backups. So there are no other incoming connections than web mail access and SMTP for local devices.
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Hello all,
 
today I saw that the message retrieval wasn't working again. The POP retrieval log showed only "Starting processing for ...".
 
Looking at the opened TCP ports I could see that SmarterMail didn't close a POP3s connection to the mail provider (in the last both cases it was Microsoft). In the POP retrieval log you can see:
 
18:37:32 [...] [...] Connection to 65.55.162.199 succeeded
18:37:32 [...] [...] CMD: USER <...>
18:37:33 [...] [...] CMD: PASS XXXX
18:37:37 [...] [...] CMD: STAT
 
So there's no QUIT entry in the log. After closing this TCP connection SmarterMail still isn't able to do POP3 retrievals. I have to restart the SmarterMail service and then the retrieval is working again.
 
I don't believe there's an issue related to Windows 10 because the TCP connection is established. But it wouldn't be closed sometimes. I can also say that there's no relationship to the hourly backup because this happens to full hour times, i. e. 17:00, 18:00 and so on.
 
Who should close the connection? Should SmarterMail close it? Why this doesn't happen sometimes?
 
Thank you.
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Today, I had the same issue: Yesterday at nearly the same time there was no QUIT and the POP3s connection to Microsoft was still active. No later POP3 retrieval was successful.

So I had to restart the SmarterMail service again to get the POP retrieval working.
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Again today, near to 18:00 the POP3s connection to Microsoft wasn't closed by QUIT. Only the restart of the SmarterMail service solved the issue.
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Hello all,
 
for me it looks like SmarterMail isn't sometimes sending the QUIT command for closing the POP3(s) connection. Shouldn't there be a timeout for a open session which then will be closed by a QUIT command?
 
This seems to happen with the POP3s connection to Microsoft only. With GMX as my second mail provider I don't have this issue.
 
The protocol settings in my SmarterMail installation are the default settings so there is a timeout activated for the POP protocol. But does this timeout also belong to POP retrieval of SmarterMail itself (when it's retrieving mails from another mail server) or is this setting only related to POP retrievals from mail clients connecting to the SmarterMail server?
 
Thank You.
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With a LEGAL 2012R2 licence, Microsoft can help you to activate.
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Thanks for this hint ;-) I tried the reactivation of my legal licence at Microsoft but without success so far. And that's why I'm running the workaround with Windows 10 until I get my license reactivated.
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You can use a 2012 R2 evaluation version.
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Yesterday, at 23:52 the POP3s connection to Microsoft wasn't closed by QUIT. Only the restart of the SmarterMail service solved the issue.
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Yes, you're right. But if you look at the end of my thread you can see that I don't think that the issue is related Windows 10 because of TCP connection limitations. Sometimes SmarterMail doesn't send the QUIT command for closing the POP3s connection to Microsoft. I don't see this issue for a POP3s connection to GMX.
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Yesterday, at 22:54 the POP3s connection to Microsoft wasn't closed by QUIT. Only the restart of the SmarterMail service solved the issue.
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Hello all,
 
does nobody know this issue or can help troubleshooting?
 
Kind Regards.
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Today, at 00:46 the POP3s connection to Microsoft wasn't closed by QUIT. Only the restart of the SmarterMail service solved the issue.
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Bruce Barnes Replied
Put SmarterMail on a real server installation, using the latesy version of 15,X, and your problems will dissapear.

General operating systems csn have a max if 20 ports open, and this includes the printer, files, locale login, and anything else connected.

Many make multiple connections, further limiting connectivity availability.
Bruce Barnes
ChicagoNetTech Inc
brucecnt@comcast.net

Phonr: (773) 491-9019
Phone: (224) 444-0169

E-Mail and DNS Security Specialist
Network Security Specialist

Customer Service Portal: https://portal.chicagonettech.com
Website: https://www.ChicagoNetTech.com
Security Blog: http://networkbastion.blogspot.com/

Web and E-Mail Hosting, E-Mail Security and Consulting
0
As I often wrote this isn't a problem of the limitation of concurrent connections because it's a outgoing connection and not a incomming one - the limitation is only regarding to incomming connections. And I see that the connection is established but won't be closed sometimes. And I'm using the latest 15.x release of SmarterMail which is 15.4.6151.
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Paul Blank Replied
Wish I could be of more assistance but here's what I think: it seems to be either that connection limit problem or a bug. Oh yes, and make sure your Windows firewall is turned off, and, at least as a test, completely uninstall all anti-virus programs (don't just disable them!).
 
Next comment: you can download a trial of Windows server, and it will run for 6 months, after which time you can extend the trial ("rearm" command - look it up). You can also buy fully licensed, genuine sealed OEM versions of Windows server on places like ebay for under $ 200.00.
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Bruce Barnes Replied
The more I see of your responses, the more I think all you want to do is argue.

I beg to differ with you, but conections are accumulated by both incoming, and outgoing, connections on all services.

They also count printer and drive mappings - whether temporary, or permanent.

All versions of SmarterTools products must now be installed on a server operating system, preferably 12.X, or above,, with .NET 4.5, and all security patches installed.

All SmarterTools production must run ubder IIS, and the SmarterTools / SmarterMail internal web server must be disabled.

Ports 110, 25, and 587 must be open, at, the very minimum. There are other TLS ports which should also e opened as well.

This will also enable TLS, if the sending MX server supports it, and will also ensure that clients who connect via, or travel through Comcast, which, unceremoniously blocks connections through port 25.

Just my humble opinion - based on experiance gained working with e-mail since it's infancy, in the middle 1980s.

End of discussion and response on my side.
Bruce Barnes
ChicagoNetTech Inc
brucecnt@comcast.net

Phonr: (773) 491-9019
Phone: (224) 444-0169

E-Mail and DNS Security Specialist
Network Security Specialist

Customer Service Portal: https://portal.chicagonettech.com
Website: https://www.ChicagoNetTech.com
Security Blog: http://networkbastion.blogspot.com/

Web and E-Mail Hosting, E-Mail Security and Consulting
0
Mail Server Replied
Hi,
 
I user SmarterMail (latest 15 version) on Server 2008 (not R2) for several years, and since 2 weeks I have the same issue. The pop retrieval process didn't close the connection for only one user. After theis happens, the Mailserver process uses 100% cpu. If I stop and restart the pop retrival service inside smartermail, nothing changes.Only workaround is the restart of the whole SmarterMail windows service.
Even lower the pop3 timeount (for the incomming connections?) did't change the issue.
 
Hint: The failing user has more than 1.000 mail in his inbox. Thats the only difference compared to the oter users. Pop retrieval puts the mails in the inbox ... provider is the same for all users. Uses Unix/Linux based mailserver for millions of accounts.
 
Hope this helps to find the issue.
 
Best regaards
 
Lars
 
 
 
1
Paul Blank Replied
"Mail Server," in your case it sounds as if SM is choking on that large mailbox. One fix for this might be to move all, or most of, the already-retrieved emails to another mailbox (under that same user) in SM. That would make SM not need to "traverse" all those other emails when it goes to retrieve.
 
If all those emails are on the mail server, because all clients for that user "leave mail on server," and that is causing the problem, then you probably need to clean out or move the emails on the mail server. And yes, in either event it sounds like bug in SM, which should not choke on these.
 
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Mail Server Replied
Hi Paul,
the user "purged/cleaned" his Inbox. There are 150 Mails left. Seems that this does not help ... one hanger since this. I will observe further on an come back after some days. At ehe moment I keep the service running with automatic restart by "Service Protector" ...
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Mail Server Replied
Still hanger. Try to "touch" Pop Retrieval Settings for all users ... modify save ... modify back save.
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Mail Server Replied
After this another user hangs ... which never hangs before ... really strange. So it could not be an content driven problem caused by the specific data of an user.
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Mail Server Replied
In all cases the last command shown in the logs are:

09:39:57 [userXY@domain.net] [SSL-pop-server-of-provider:userXY@domain.net] CMD: QUIT

but no

09:40:02 Finished processing for userXY@domain.net

shown. After this the CPU rises to 100%. The other users seems to work properly, New process are startet for userXY, but never ever an Finsihed line are shown.
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Paul Blank Replied
Confusing! Possible glitch in SM user account? What happens if you create another SM user and try the same POP retrieval process from the original user into the new SM account?
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Mail Server Replied
Hi, thanks for the reply and idea. Not really easy, cause I don't know how to provide the retrieved mails to the "real" user. Only idea is to configure the test user pop retrievel to leave the mails on the server ...
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Mail Server Replied
Try delete and set up from scratch the popretrieval for the user. No change. Setup the same popretrieval for a second user (with keep on server). Didn't stop working the last hours.
So what could be the issue with the user affected, that stops the popretievel from time to time. Approx. 1-3 time a day?
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Mail Server Replied
O.k. new observation. MailService uses 100% cause the popretrieval stops for another user.
So it's not an user mailbox problem.
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Paul Blank Replied
Perplexing still. Perhaps there is some glitch in the user's settings (or a bad file) on the mail server you're retrieving from (creating an incompatibility with the SM process?). At this point it's the only other thing I can think of.
 
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Mail Server Replied
Yes, but it's a little bit "sppoky" that suddenly something went wrong in different users accounts.
I wonder, it it would be a good idea to hard kill the popretrieval process for an user, if it didn't come to an end. But this depends on the internal arcitecture of the MailService process.
However, I try to analyse with sysinternals procesmonitor, but can't find any hint whts going wrong, when the process runns with 100% cpu ...
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Mail Server Replied
Dear Paul,
 
since my 2008 server go end of support, I setup a new one 2016 Standard. Copy the xml config files out of the programm tree and robocopy the mail store to the new server.
 
Same behaviour.
 
Only possibility to stay online is Service Protector ,,,
 
Do you have any hint how to debug? Log is set to Detailed for Pop-Retrieval.
 
Regards
 
Lars
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After switching my Windows 10 virtual machine to another ESX host the POP3s retrieving of mails is working fine with all mail provider. It seems that my first host wasn't able to give enough CPU and I/O resources to the virtual machine for finalizing the mail retrieval at some time.

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