Cannot mail via mail client

vromanr

Hi,

I’m running dockerized mailcow on Almalinux 9. Sinds a few updates back problems started with sending e-mails via a mail client like apple mail and Thunderbird. At this moment I cannot send any mail via a client, but I can only via Sogo.

Via tcpdump I can see the sessions comming into the server on ports 25 or 465. I have been thru all the logs, but found nothing weird.

Does somebody has a suggestion what might be the problem ?

Thanks in advance.

Remco

D4niel

You should check the logs of the postfix container. Is there any connection?

vromanr

Hi Ares,

thanks for looking into this.

Yes, there seem to be connections:

Tijd Prioriteit Bericht
15-02-2023 22:03:26 info connect from 095-096-245-038.static.chello.nl[95.96.245.38]
15-02-2023 22:03:26 info disconnect from 095-096-245-038.static.chello.nl[95.96.245.38] commands=0/0
15-02-2023 22:03:26 info lost connection after CONNECT from 095-096-245-038.static.chello.nl[95.96.245.38]
15-02-2023 22:03:26 info SSL_accept error from 095-096-245-038.static.chello.nl[95.96.245.38]: lost connection
15-02-2023 21:58:52 info disconnect from 095-096-245-038.static.chello.nl[95.96.245.38] commands=0/0
15-02-2023 21:58:52 info lost connection after CONNECT from 095-096-245-038.static.chello.nl[95.96.245.38]
15-02-2023 21:58:52 info SSL_accept error from 095-096-245-038.static.chello.nl[95.96.245.38]: lost connection
15-02-2023 21:58:26 info connect from 095-096-245-038.static.chello.nl[95.96.245.38]
15-02-2023 21:58:26 info disconnect from 095-096-245-038.static.chello.nl[95.96.245.38] commands=0/0
15-02-2023 21:58:26 info lost connection after CONNECT from 095-096-245-038.static.chello.nl[95.96.245.38]

D4niel

SSL_accept error

I guess there’s a problem with your SSL certificates or configuration.
Maybe you can do some tests to get some insight: https://www.checktls.com/TestReceiver

vromanr

seconds test stage and result
[000.000] Trying TLS on mail.zondagskinderen.net[185.189.183.244:25] (-1)
[000.084] Server answered
[005.052] <‑‑ 220-mail.zondagskinderen.net ESMTP Postcow
220 mail.zondagskinderen.net ESMTP Postcow
[005.053] We are allowed to connect
[005.053] ‑‑> EHLO www12-azure.checktls.com
[005.136] <‑‑ 250-mail.zondagskinderen.net
250-PIPELINING
250-SIZE 104857600
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250 CHUNKING
[005.136] We can use this server
[005.136] TLS is an option on this server
[005.136] ‑‑> STARTTLS
[005.218] <‑‑ 220 2.0.0 Ready to start TLS
[005.219] STARTTLS command works on this server
[005.399] Connection converted to SSL
SSLVersion in use: TLSv1_3
Cipher in use: TLS_AES_256_GCM_SHA384
Perfect Forward Secrecy: yes
Session Algorithm in use: Curve X25519 DHE(253 bits)
Certificate #1 of 4 (sent by MX):
Cert VALIDATED: ok
Cert Hostname VERIFIED (mail.zondagskinderen.net = mail.zondagskinderen.net | DNS:mail.zondagskinderen.net)
Not Valid Before: Feb 15 17:13:14 2023 GMT
Not Valid After: May 16 17:13:13 2023 GMT
subject: /CN=mail.zondagskinderen.net
issuer: /C=US/O=Let’s Encrypt/CN=R3
Certificate #2 of 4 (sent by MX):
Cert VALIDATED: ok
Not Valid Before: Sep 4 00:00:00 2020 GMT
Not Valid After: Sep 15 16:00:00 2025 GMT
subject: /C=US/O=Let’s Encrypt/CN=R3
issuer: /C=US/O=Internet Security Research Group/CN=ISRG Root X1
Certificate #3 of 4 (added from CA Root Store):
Cert VALIDATED: ok
Not Valid Before: Jun 4 11:04:38 2015 GMT
Not Valid After: Jun 4 11:04:38 2035 GMT
subject: /C=US/O=Internet Security Research Group/CN=ISRG Root X1
issuer: /C=US/O=Internet Security Research Group/CN=ISRG Root X1
Certificate #4 of 4 (sent by MX):
Cert VALIDATED:
Not Valid Before: Jan 20 19:14:03 2021 GMT
Not Valid After: Sep 30 18:14:03 2024 GMT
subject: /C=US/O=Internet Security Research Group/CN=ISRG Root X1
issuer: /O=Digital Signature Trust Co./CN=DST Root CA X3
[005.514] > EHLO www12-azure.checktls.com
[005.598] < 250-mail.zondagskinderen.net
250-PIPELINING
250-SIZE 104857600
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250 CHUNKING
[005.598] TLS successfully started on this server
[005.598] > MAIL FROM:test@checktls.com
[005.687] < 250 2.1.0 Ok
[005.687] Sender is OK
[005.687] > QUIT
[005.770] < 221 2.0.0 Bye

Seems all good

vromanr

In my search to solve this issue I found these remarks during starting Mailcow:
WARN[0000] The “c” variable is not set. Defaulting to a blank string.
WARN[0000] The “c” variable is not set. Defaulting to a blank string.
WARN[0000] The “c” variable is not set. Defaulting to a blank string.

I found a suggestion to solve this issue by disabling ipv6. I did so according to this procedure: https://docs.mailcow.email/post_installation/firststeps-disable_ipv6/

That did not solve the warnings.

The mail client does still not work, any suggestions ?

D4niel

It’s a bit hard to troubleshoot, but I don’t see an issue with your mail server from the outside. Are you sure it’s not a client problem? Have you tried setting up a email account on another device?
What are the error messages in the mail client?

vromanr

I have tried Apple mail, Thunderbird, MS outlook, they all time-out on authentication.

Thunderbird was complaning about certs, at first but toen time-out as well