Check that it's running
First check with ps that dovecot process is actually running. If it's not, you had an error in dovecot.conf and the error message was written to log. Go back to RunningDovecot and Logging if you can't find it.
Check that it's listening
Next check that Dovecot is listening for connections:
# telnet localhost 110 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. +OK Dovecot ready.
If you got "connection refused", check that pop3 is included in protocols setting in dovecot.conf. Also check that listen setting is *.
Next check that it also works from remote host:
# telnet imap.example.com 110 Trying 18.104.22.168... Connected to imap.example.com. Escape character is '^]'. +OK Dovecot ready.
If that didn't work, check all possible firewalls in between, and check that listen setting is * in dovecot.conf.
Check that it's allowing logins
# telnet localhost 110 user username pass password
Replace the username and password with the ones you added to passwd.dovecot in BasicConfiguration.
You should get an "+OK Logged in." reply. If you get "Authentication failed" error, set auth_verbose = yes and auth_debug = yes in dovecot.conf, restart Dovecot and try again. The log file should now show enough information to help you fix the problem.
Check that it's allowing remote logins
You'll need to try this from another computer, since all local IPs are treated as secure:
# telnet imap.example.com 110 user username pass password
If the connection is hanging instead of giving +OK Dovecot ready, you have a firewall that's preventing the connections.
Otherwise, the only difference here compared to step above is that you might get:
-ERR Plaintext authentication disabled.
If this is the case, you didn't set disable_plaintext_auth = no. You could alternatively use OpenSSL to test that the server works with SSL (assuming you've already set it up):
# openssl s_client -connect imap.example.com:995 +OK Dovecot ready.
Check that it finds the mails
After logging in, check that it sees mails:
stat +OK 1 1532 retr 1 +OK 1532 octets <the mail's contents> .
It should contain the mail that you sent to yourself in FindMailLocation step.
If anything goes wrong, set mail_debug = yes and try again. The log file should now contain debugging information of where Dovecot is trying to find the mails. Fix mail_location setting and try again.
Check that real mail clients work
Since mail clients can be configured in various ways, please check first if the problem is with Dovecot configuration or with the client's configuration. You can rule out it being Dovecot's problem with the "telnet" methods described above.
If you can't log in,
- Make sure SSL/TLS settings are correct.
- Make sure the client uses plaintext authentication method, unless you've specifically configured Dovecot to accept others.
Many POP3 clients have been tested with Dovecot and they work.
Make a graceful exit
To close the connection to Dovecot issue a logout:
quit +OK Logging out.