[Dovecot] avoid log message when using nagios check

Hello, I'm using a nagios check to monitor dovecot status, since dovecot v2 I see those syslog messages on every nagios check:

pop3-login: Aborted login (no auth attempts in 0 secs) imap-login: Aborted login (no auth attempts in 0 secs)

I tried to avoid those messages sending a logout string:

check_imap -H localhost -e 'OK' -s 'a logout' check_pop -H localhost -e 'OK' -s 'quit'

but now I get

imap-login: Disconnected (no auth attempts in 0 secs) pop3-login: Disconnected (no auth attempts in 0 secs)

what can I do to avoid a log message on every nagios check?

thanks! Lluís