1 Topic by LaurentM

  • LaurentM
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Topic: IMAPS not answering

Hello,

I am facing a strange behavior with Dovecot 2.4 on Debian Trixie.
When I try to connect to the IMAP server, on port 143 it is answering correctly, but the IMAPS on port 993 does not listen correctly.

Connection to IMAP port 143:

# telnet 192.168.10.205 143
Trying 192.168.10.205...
Connected to 192.168.10.205.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 LOGIN-REFERRALS ID ENABLE IDLE SASL-IR LITERAL+ STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot ready.
1 login <username> <userpassword>
1 OK [CAPABILITY IMAP4rev1 SASL-IR LOGIN-REFERRALS ID ENABLE IDLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS THREAD=ORDEREDSUBJECT MULTIAPPEND URL-PARTIAL CATENATE UNSELECT CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS BINARY MOVE REPLACE SNIPPET=FUZZY PREVIEW=FUZZY PREVIEW SPECIAL-USE STATUS=SIZE SAVEDATE COMPRESS=DEFLATE INPROGRESS NOTIFY METADATA LITERAL+ QUOTA ACL RIGHTS=texk LIST-MYRIGHTS] Logged in
2 logout
* BYE Logging out
2 OK Logout completed (0.001 + 0.000 secs).
Connection closed by foreign host.

Connection to IMAPS port 993

# telnet 192.168.10.205 993
Trying 192.168.10.205...
Connected to 192.168.10.205.
Escape character is '^]'.
1 login <username> <userpassword>
Connection closed by foreign host.

After the telnet connection to port 993 I never receive the "*OK CAPABILITY... Dovecot ready." answer.

If anyone as a clue.

----

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2 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
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Re: IMAPS not answering

this is correct and expected because telnet doesn't support secure connection at all. Use a MUA like Thunderbird for testing, or a command line tool which supports secure connection, or Python/Perl/php/... script.

3 Reply by LaurentM

  • LaurentM
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Re: IMAPS not answering

OK, I understand.

But now, with Thunderbird, when I try to connect to my mail server I get the warning message that the server is not securised as it doesn't use encryption, and thunderbird uses IMAP with STARTTLS.

Should I setup the let's encrypt certificate in dovecot/postfix for securing the server?

4 Reply by LaurentM

  • LaurentM
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Re: IMAPS not answering

OK, my mistake again.

I followed the https://docs.iredmail.org/use.a.bought. … icate.html tutorial and this fixed the issue after restarting the dovecot and postfix service.

Instead of copying the certificates I created a link to them as they are in automatic renewal with letsencrypt.
I also created a postconf script to restart dovecot/postfix services after renewal.