IMAP connection lost while sending mail

Paul Kudla (SCOM.CA Internet Services Inc.) paul at scom.ca
Fri May 6 15:00:58 UTC 2022


OK this is starting to make more sense

 >>>

Time it. Is it hitting a specific time and giving up?

 > It looks like there is instant problem, Outlook reporting problem 
Moving Mail into "Sent"

<<<


Note one more issue with using Outlook past 2012

YOU MUST GOTO the control panel (old one in win 10) and use the Mail 
Setup - Outlook (32bit)

Outlook itself seems to block any real access to the advanced settings.

That being Said ....

Ok Outlook imap may have the sent folder destination setup wrong?

first off with dovecot use the default Folder

(Root folder path option box == Blank)

Next thing to check (and microsoft moved this around)

Is the destination imap folder top place a sent copy in

2019 seems to be here ?

Home (in top bar) then Rules (aprox 2/3's over)

apparently you need to create a rule to change the destination folder?

previous outlook versions have a place a copy in this folder option 
(fyi) in the advanced setup via the control panel.

In general imap returns all the special folders when logging into the server

The issue with outlook and outlook 365 is they tend to make a Sent 
folder (for example) in the root path of the imap account

or

something under the INBOX (Like INBOX/Sent)

at the end of the day if you have access to the Dovecot Server check the 
mail dir structure

verify where the sent folder is

below is from an old cyrus import (to give an example of what might be 
happening) you will notice that there is NO .Sent folder but a 
INBOX.Sent folder

 >>>

drwx------    5 vmail  vmail  uarch    8B May  6 05:10 .INBOX.Drafts
drwx------    5 vmail  vmail  uarch    9B May  6 05:10 .INBOX.Sent
drwx------    5 vmail  vmail  uarch    8B May  6 05:10 .INBOX.Trash
-rw-------    1 vmail  vmail  uarch  571B May  3 15:18 .dovecot.lda-dupes
drwx------    5 vmail  vmail  uarch    9B May  6 05:10 
.dovecot.lda-dupes.locks
drwx------    2 vmail  vmail  uarch    2B Apr  2 13:11 cur
-rw-------    1 vmail  vmail  uarch  5.6K May  5 13:29 dovecot-uidlist
-rw-------    1 vmail  vmail  uarch    8B May  1 13:05 dovecot-uidvalidity
-r--r--r--    1 vmail  vmail  uarch    0B Feb 20 07:16 
dovecot-uidvalidity.6212313e
-rw-------    1 vmail  vmail  uarch  2.5K May  5 13:29 dovecot.index
-rw-------    1 vmail  vmail  uarch   28K May  6 05:10 dovecot.index.cache
-rw-------    1 vmail  vmail  uarch  568B May  6 05:10 dovecot.index.log
-rw-------    1 vmail  vmail  uarch   32K May  5 13:29 dovecot.index.log.2
-rw-------    1 vmail  vmail  uarch  1.3K May  3 05:10 dovecot.list.index
-rw-------    1 vmail  vmail  uarch  7.2K May  6 05:10 
dovecot.list.index.log
-rw-------    1 vmail  vmail  uarch  168B Feb 20 08:03 dovecot.mailbox.log
drwx------    2 vmail  vmail  uarch   95B May  5 13:29 new
drwx------    4 vmail  vmail  uarch    7B May  5 13:29 sieve
-rw-------    1 vmail  vmail  uarch   77B Feb 20 08:03 subscriptions
drwx------    2 vmail  vmail  uarch    2B May  5 13:29 tmp

<<<

Below is a Normal Dovecot Struxture (from my experience)

 >>>

drwx------  28 vmail  vmail  uarch   42B May  6 10:16 .
drwx------   4 vmail  vmail  uarch    4B Feb 19 17:58 ..
drwx------   5 vmail  vmail  uarch   10B May  6 06:21 .Drafts
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2010
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2011
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2012
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2013
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2014
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2015
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2016
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2017
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2018
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2019
drwx------   5 vmail  vmail  uarch   11B May  6 06:21 .INBOX.Archives.2020
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Archives.2021
drwx------   5 vmail  vmail  uarch   10B May  6 06:21 .INBOX.Archives.2022
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 
.INBOX.Archives.Sent 2022
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Junk
drwx------   5 vmail  vmail  uarch    9B May  6 06:21 .INBOX.Notes
drwx------   5 vmail  vmail  uarch   10B May  6 06:21 .INBOX.Trash
drwx------   5 vmail  vmail  uarch   12B May  6 08:41 .Sent
drwx------   5 vmail  vmail  uarch   11B May  6 08:40 .Trash
-rw-------   1 vmail  vmail  uarch   51B May  6 06:35 .dovecot.lda-dupes
drwx------   5 vmail  vmail  uarch    9B May  6 06:35 
.dovecot.lda-dupes.locks
drwx------   2 vmail  vmail  uarch  1.8K May  6 09:08 cur
-rw-------   1 vmail  vmail  uarch   52B Apr 26 08:03 dovecot-keywords
-rw-------   1 vmail  vmail  uarch  131K May  6 09:08 dovecot-uidlist
-rw-------   1 vmail  vmail  uarch    8B May  2 10:25 dovecot-uidvalidity
-r--r--r--   1 vmail  vmail  uarch    0B Feb 19 17:58 
dovecot-uidvalidity.62117625
-rw-------   1 vmail  vmail  uarch   45K May  6 08:41 dovecot.index
-rw-------   1 vmail  vmail  uarch  1.8M May  6 10:16 dovecot.index.cache
-rw-------   1 vmail  vmail  uarch   26K May  6 09:09 dovecot.index.log
-rw-------   1 vmail  vmail  uarch   32K May  4 10:56 dovecot.index.log.2
-rw-------   1 vmail  vmail  uarch  2.7K May  6 06:21 dovecot.list.index
-rw-------   1 vmail  vmail  uarch  5.0K May  6 09:08 dovecot.list.index.log
-rw-------   1 vmail  vmail  uarch  2.2K May  2 10:25 dovecot.mailbox.log
-rw-------   1 vmail  vmail  uarch    0B Feb 19 17:58 maildirfolder
drwx------   2 vmail  vmail  uarch    2B May  6 09:08 new
drwx------   4 vmail  vmail  uarch    4B Feb 27 16:44 sieve
-rw-------   1 vmail  vmail  uarch  364B May  2 10:25 subscriptions
drwx------   2 vmail  vmail  uarch    2B May  6 09:08 tmp

<<<

Notice the .Sent, .Trash folders are in the root.

this is what dovecot is probably returning in the login imap parameters

However if you are using INBOX/Sent then outlook is probably getting 
confusing thus causing the error ie the box would not be accessable.

another note do you have the auto creation turned on for the imap folders ?

namespace inbox {
   inbox = yes
   location =
   mailbox Drafts {
     auto = subscribe
     special_use = \Drafts
   }
   mailbox Sent {
     auto = subscribe
     special_use = \Sent
   }
   mailbox Trash {
     auto = subscribe
     special_use = \Trash
   }
   prefix =
   separator = /
}


If not then outlook would be able to autocreate the Special Folders

I found that when migrating from cyrus imap i ended up with 2 sets of 
special folders which athough a mess was explanable because of what i am 
mentioning here.

if you turn on the auto create and restart dovecot chances are this 
might deal with your Special Folders as they will be re-created as per 
what / how outlook want to access them. (hopefully)



Another note is the subscriptions file in the maildir

# cat subscriptions
V       2

INBOX
Drafts
Sent
INBOX   Archives        2010
INBOX   Archives        2011
INBOX   Archives
INBOX   Archives        2012
INBOX   Archives        2013
INBOX   Archives        2014
INBOX   Archives        2015
INBOX   Archives        2016
INBOX   Archives        2017
INBOX   Archives        2018
INBOX   Archives        2019
INBOX   Archives        2020
INBOX   Archives        2021
INBOX   Junk
INBOX   Notes
Trash
INBOX   Archives        2022
INBOX   Archives        Sent 2022
INBOX   Trash

this file sets the imap folder list and dir structure.

I found i had to manually fix some of these entries when moving from 
cyrus to dovecot

this file is the folder list that is sent to the IMAP email client and 
some times will not update correctly. (thunderbird as an example a lot 
of greyed out inaccessable folders were in this file and had to be removed)



Happy Hunting ....




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 10:30 AM, Philipp Ewald wrote:
> Hello Paul and Kevin,
> 
> 
> thanks for your replys!
> 
> Problem is, i am Administrator from mail Server and customer has there 
> own administrator.
> Me and the other IT don't know whats the problem is.
> 
> 
> I will tell them too do some more testing and maybe switching 
> Mailclient, Outlooks is horrible...
> I will try other Ports and ask if there can clean up the mailbox (PC was 
> already cleaned and still not work)
> 
> On time i was there and i had no problem with my Linux + Thunderbird... 
> so network is working.
> 
>> 1 - Time it. Is it hitting a specific time and giving up?
> It looks like there is instant problem, Outlook reporting problem Moving 
> Mail into "Sent"
> 
>> 2 - Does the email have any specific content?
> its random problem, mostly this error happen when there are some more 
> recipient, but sometime problem with less recipient.
> 
>> 3 - Do they have anything like A/V software that might be acting to 
>> try and proxy / scan the email?
> there told me there has tested on a new installed windows with out any 
> "rules/extra software" applied on
> 
> 
> Thanks i will report if we had some success.
> 
> 
> Have a nice weekend!
> 
> Am 06.05.22 um 12:55 schrieb Paul Kudla (SCOM.CA Internet Services Inc.):
>>
>> 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
>>>
> 


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