My maillog file is flooded with
Jun 15 14:30:25 server postfix/pickup[16819]: D601340A02: uid=0 from=
Jun 15 14:30:25 server postfix/cleanup[25686]: D601340A02: message-id=
Jun 15 14:30:25 server postfix/cleanup[25686]: D601340A02: milter-reject: END-OF-MESSAGE from localhost[127.0.0.1]: 4.7.1 Service unavailable - try again later; from= to=
Im getting it every minute. Is this normal?