To see which Dovecot users sign in to retrieve or send emails, you can use the doveadm command to query the logs. Here’s a step-by-step guide:

Step 1. Enable Logging

Ensure that Dovecot is configured to log authentication attempts. You can do this by editing the dovecot.conf file:

log_path = /var/log/dovecot.log
auth_verbose = yes

Step 2. Check the Logs

You can use the grep command to filter the logs for login attempts. For example:

grep 'Login:' /var/log/dovecot.log

Alternatively, you can use the doveadm command to query user information. For example, to check user logins:

doveadm log find

If you want to monitor user log-ins to Dovecot in real-time, you can use the tail command:

tail -f /var/log/dovecot.log | grep 'Login:'

These steps will help you track which users are signing in to retrieve or send emails through Dovecot.