Dovecot 2.3.11.3 LMTP dropping connection after first part of multipart message received

[Steve Akerman]

Good afternoon

Problem Solved!

After some very useful input from John Fawcett, I have identified that the problem was not Dovecot, but the mailer used for Dovecot in Sendmail; it was missing the F=X flag that double dots any single dots, which are rather common in messages that were badly truncated to 75 line length by Apple Mail and Outlook amongst others.

The correct Mailer spec for Dovecot LMTP is:

######################*****##############
### DOVECOT Mailer specification ###
##################*****##################
Mdovecot, P=[IPC], F=zDFMPXhnul59,
        S=EnvFromSMTP/HdrFromSMTP, R=EnvToSMTP/HdrFromSMTP,
        T=DNS/RFC822/X-Unix,
        A=FILE /var/run/dovecot/lmtp

which should be in a file called Dovecot inside sendmail cf/mailers and included in the site mc file as

MAILER(`dovecot’)dnl

As this information is missing from the very good WIKI, could someone add it in order to help others in the future?

Thanks

Steve


> On 10 Dec 2020, at 14:58, Steve Akerman <steve.akerman at aboukir.com> wrote:
> 
> Good afternoon
> 
> I have been using Dovecot with great success for several months now with one problem:
> 
> I have received several messages (3 to date out of a much larger number) which cause Dovecot LMTP to drop the connection with sendmail after only receiving the first part of the message.
> 
> Dovecot saves the first part to INBOX, and then drops the link with sendmail as it sees the rest of the data from sendmail as new (and invalid) commands
> 
> Sendmail sees the delivery as unsuccessful and requeues the message, so the cycle continues until i kill the queue
> 
> These messages are all Multipart MIME
> 
> I have attached an extract from the log which shows the above sequence
> 
> Finally, I have kept one such message from the sendmail queue (df and qf) should this be useful, but prefer not to post here as not sanitised 
> 
> Any help in correcting my configuration would be appreciated.
> 
> Thanks
> 
> Steve
> 
> 
> MAIL LOG extract
> -------------------------
> 
> Dec  9 12:00:10 phone dovecot[179]: lmtp(20774): Connect from local
> Dec  9 12:00:10 phone sm-mta-rx[20764]: STARTTLS=client, relay=localhost, version=TLSv1.3, verify=OK, cipher=TLS_AES_256_GCM_SHA384, bits=256/256
> Dec  9 12:00:10 phone dovecot[179]: lmtp(20775): Connect from local
> Dec  9 12:00:10 phone sm-mta-rx[20763]: STARTTLS=client, relay=localhost, version=TLSv1.3, verify=OK, cipher=TLS_AES_256_GCM_SHA384, bits=256/256
> Dec  9 12:00:10 phone dovecot[179]: lmtp(*********)<20775><8EieKDqu0F8nUQAA0J78UA>: msgid=<39113a86-fdbb-4cea-b1c3-d225dff93328 at info.ameli.fr <mailto:39113a86-fdbb-4cea-b1c3-d225dff93328 at info.ameli.fr>>: saved mail to INBOX
> Dec  9 12:00:10 phone dovecot[179]: lmtp(20775): Disconnect from local: Too many invalid commands. (state=READY)
> Dec  9 12:00:10 phone sm-mta-rx[20763]: STARTTLS: write error=syscall error (-1), errno=32, get_error=error:00000000:lib(0):func(0):reason(0), retry=1, ssl_err=5
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803: SYSERR(root): timeout writing message to localhost: Broken pipe
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   0: fl=0x0, mode=20666: CHR: dev=30/1306024, ino=301, nlink=1, u/gid=0/0, size=0
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   1: fl=0x1, mode=20666: CHR: dev=30/1306024, ino=301, nlink=1, u/gid=0/0, size=0
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   2: fl=0x1, mode=20666: CHR: dev=30/1306024, ino=301, nlink=1, u/gid=0/0, size=0
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   3: fl=0x4002, mode=100600: dev=1/2, ino=26089780, nlink=1, u/gid=0/23, size=2041
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   4: fl=0x0, mode=20666: CHR: dev=30/1306024, ino=575, nlink=1, u/gid=0/0, size=0
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   5: fl=0x2, mode=140666: SOCK localhost->[[UNIX: /var/run/mDNSResponder]]
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   6: fl=0x0, mode=100640: dev=1/2, ino=25887976, nlink=1, u/gid=0/23, size=12288
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   7: fl=0x0, mode=100640: dev=1/2, ino=25887976, nlink=1, u/gid=0/23, size=12288
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   8: fl=0x0, mode=100600: dev=1/2, ino=26088246, nlink=1, u/gid=0/23, size=58024
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:   9: fl=0x6, mode=140444: SOCK localhost->(Invalid argument)
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:  10: fl=0x6, mode=140444: SOCK localhost->(Invalid argument)
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:  11: fl=0x0, mode=100640: dev=1/2, ino=25768590, nlink=1, u/gid=0/23, size=12288
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803:  12: fl=0x0, mode=100640: dev=1/2, ino=25768590, nlink=1, u/gid=0/23, size=12288
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803: MCI at 0x0: NULL
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803: MCI at 0x7fae2c814818: flags=26404c<CACHED,ESMTP,8BITMIME,INMIME,ENHSTAT,PIPELINED,TLSACT>, errno=32, herrno=0, exitstat=75, state=8, pid=0, maxsize=0, phase=client DATA 354, mailer=dovecot, status=4.4.2, rstatus=(null), host=localhost, lastuse=Wed Dec  9 12:00:10 2020\n
> Dec  9 12:00:10 phone sm-mta-rx[20763]: 0B89mOON016803: to=<s****************>, delay=1+01:11:31, xdelay=00:00:00, mailer=dovecot, pri=4787366, relay=localhost, dsn=4.4.2, reply=75, stat=Deferred
> 
> 
> ######################*****##############
> ### DOVECOT Mailer specification ###
> ##################*****##################
> Mdovecot, P=[IPC], F=zDFMPhnul59,
>         S=EnvFromSMTP/HdrFromSMTP, R=EnvToSMTP/HdrFromSMTP,
>         T=DNS/RFC822/X-Unix,
>         A=FILE /var/run/dovecot/lmtp
> 
> 
> 

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