I can't describe it properly, but I have a Thunderbird mail client, I use it to receive and send mail through a user I created and an available domain. I use IMAP and POP3 services there, I also have SMTP set up, I have created mail client users in the MySQL database. I have both Postfix and Dovecot set up via the LMTP protocol. I can no longer use the locally created users on my VPS, because I have disabled local users. But I can authenticate these local users even though it says "authentication failed" but it takes a very long time.
My problem is that SMTP login, SASL authentication, Telnet login via IMAP and POP3 services work for me, but as shown in the code below, the login takes some time. Between 10 and 30 seconds and I don't know why. It should do it immediately. I don't understand what could be wrongly set up, since both sending and receiving messages work for me. Only when sending, Thunderbird waits a long time before logging me into the SMPT server.
Sorry for my bad english. English is not my native language.
If you need to see the configuration files, I can add them.
[root@my-private-test-vps ~]# time testsaslauthd -u [email protected] -p myPassword -s smtp
0: OK "Success."
real 0m23.043s
user 0m0.002s
sys 0m0.005s
I tried different settings but nothing helped. I also couldn't find any solution to my problem anywhere on the internet.