Download latest epel-release rpm from
http://download-ib01.fedoraproject.org/pub/epel/6/x86_64/
Install epel-release rpm:

rpm -Uvh epel-release*rpm

Install bsd-mailx rpm package:

yum install bsd-mailx

with mailx you can delete the messages as follow (as root):

bsd-mailx

…
& d *
& q

and c.email_address NOT REGEXP ‘[-a-z0-9~!$%^&=+}{\\’?]+(\.[-a-z0-9~!$%^&=+}{\\’?]+)@([a-z0-9_][-a-z0-9_](\.[-a-z0-9_]+)*\.(aero|arpa|biz|com|coop|edu|gov|info|int|mil|museum|name|net|org|pro|travel|mobi|[a-z][a-z])|([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}))(:[0-9]{1,5})?’

Sicurezza OTP token

Default Ports:	Server:	Authentication:	Port:
SMTP Server (Outgoing Messages)	Non-Encrypted	AUTH	25 (or 587)
	Secure (TLS)	StartTLS	587
	Secure (SSL)	SSL	465
IMAP Server (Incoming Messages)	Non-Encrypted	AUTH	143
	Secure (TLS)	StartTLS	143
	Secure (SSL)	SSL	993

 

This list is without any warranties and not sorted alphabetically.
See also: A List of SMTP and POP3 Mail Server (Mail Server List)

Postfix Configuration Parameters