Frequently Answered Questions

Log Messages

Unable to open /etc/sasldb2

No user_deny.db

IOERROR: opening /var/lib/imap/user_deny.db: No such file or directory

No authentication

TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits new) no authentication

Debug level information, can be ignored. You can reduce verbosity by setting debug: 0 in imapd.conf(5), or by not including debug messages on the mail facility in syslog.

Unable to setsocketopt

unable to setsocketopt(IP_TOS) service ptloader/unix: Operation not supported

Informational message issued on startup. Not critical.


No X-Spam Headers

Email Blocked Using

You are seeing the following in /var/log/maillog (line breaks added for legibility):

NOQUEUE: reject: RCPT from unknown[]: 554 5.7.1 Service \
unavailable; Client host [] blocked using; \

This message indicates your SMTP server, receiving a message from the Internet, has refused the message.

The sending host (at IP address is blocked using a centralized, external service (, that keeps track of hosts and networks on the Internet with a reputation of spamming.

For more information on this service, see

You will want to continue performing these checks, but just in case you do not want to, the relevant setting in Postfix is:

# postconf smtpd_sender_restrictions

It is the responsibility of the sending host to notify the original sender the message was not delivered.