Hello, we have a strange problem. Costumer use Outlook to connect to our IMAP and SMTP Server. While sending Mails Outlooks reports connection lost. In Mail log there is no reason logged or something else. What i dont understand is that IMAP lose connetion while using SMTP. Outlloks reports problem by moving mails into Send dir. Is that a Outlook problem? i have enables debug logging and cant see any reason :( Network was already testet. any ideas? Kind regards Philipp -- Philipp Ewald Administrator DigiOnline GmbH, Probsteigasse 15 - 19, 50670 K?ln Fax: +49 221 6500-690, E-Mail: philipp.ewald at digionline.de AG K?ln HRB 27711, St.-Nr. 5215 5811 0640 Gesch?ftsf?hrer: Werner Grafenhain Informationen zum Datenschutz: www.digionline.de/ds
Paul Kudla (SCOM.CA Internet Services Inc.)
2022-May-06 10:55 UTC
IMAP connection lost while sending mail
What version of outlook is your customer using? and what internet provider (cell, dsl, cable, fiber etc) ? anything past 2010 can be a crap shoot at best. I have had many many customers try to use outlook because it is fancier interface wise but outlook just does not really support imap properly. Last time i googled this it cam back with over 2 millions hits on outlook imap issues. All suggestions fell back to connect using exchange protocol's there was no real answer. I have been testing myself with 2019 office and it seems to work kinda. On another major note with outlook it can only handle up to maybe 1000 emails per folder or it will constantly sync and spend more time doing that then anything else. Outlook also does NOT support idle. (again echange thingy) I find thunderbird works best (even though they have issues to sort out as well here and there) I run thunderbird and can comfortably run up to 10000 emails in a folder. It's a microsoft thing pushing exchange / outlook 365 against imap. This is NO Fault of Dovecot / Cyrus or any other imap server. Best suggestions for outlook look is to use Port 143 for imap (you can use ssl on port 143) Port 587 for smtp (25 is sometimes blocked by your isp) - Note on smtp connections there are some isp's blocking normal ports, i had to open up 10000 on my postfix to get around at&t blocking smtp sends from a tethered cell phone connection for one of my customers which fixed the issue. Also outlook timeouts for both send and receive should be pushed up to a couple of minutes to cover any timing issues (although 30 seconds should be ok in most cases i have found outlook to fail with unknown reasons). One more thing about outlook is to speed up the user interface in some cases they will give you an option on the bottom of the inbox to load more messages, this should be checked as i have had several customers forget about old emails and the inbox could just simply be going past 1000 messages without any kind of warning. (see above) Hope this helps Happy Friday !!! Thanks - paul Paul Kudla Scom.ca Internet Services <http://www.scom.ca> 004-1009 Byron Street South Whitby, Ontario - Canada L1N 4S3 Toronto 416.642.7266 Main?1.866.411.7266 Fax?1.888.892.7266 On 5/6/2022 3:53 AM, Philipp Ewald wrote:> Hello, > > we have a strange problem. > > Costumer use Outlook to connect to our IMAP and SMTP Server. > While sending Mails Outlooks reports connection lost. In Mail log there > is no reason logged or something else. > > What i dont understand is that IMAP lose connetion while using SMTP. > Outlloks reports problem by moving mails into Send dir. > > Is that a Outlook problem? > > i have enables debug logging and cant see any reason :( > > Network was already testet. > > > any ideas? > > Kind regards > Philipp >
On 5/6/2022 3:53 AM, Philipp Ewald wrote:> > we have a strange problem. > > Costumer use Outlook to connect to our IMAP and SMTP Server. > While sending Mails Outlooks reports connection lost. In Mail log > there is no reason logged or something else. > > What i dont understand is that IMAP lose connetion while using SMTP. > Outlloks reports problem by moving mails into Send dir. > > Is that a Outlook problem? > > i have enables debug logging and cant see any reason :( > > Network was already testet.Morning Philipp, I would do a couple of things to troubleshoot: 1 - Time it. Is it hitting a specific time and giving up? 2 - Does the email have any specific content? 3 - Do they have anything like A/V software that might be acting to try and proxy / scan the email? 4 - Try putting thunderbird on the same machine for the same account with the same email.? Does that work? Regards, KAM