I have mailserver configure using dovecot+postfix+mysql and it was runnig fine in the server(Ubuntu Server). But during last week it stopped working correctly. It doesn't send email. When I try to telnet localhost smtp I'm connecting successfully but when I do mail from:<[email protected]> and hit Enter it hangs on, nothing happen.

Having reviewed /var/log/mail.log file I've found out that probably(99%) the problem is on postfix when it is trying to connect to MySQL server. If you see the log file given below you can see that it says Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2).

Nov 14 21:54:36 ns1 dovecot: dovecot: Killed with signal 15 (by pid=7731 uid=0 code=kill)
Nov 14 21:54:36 ns1 dovecot: Dovecot v1.2.9 starting up (core dumps disabled)
Nov 14 21:54:36 ns1 dovecot: auth-worker(default): mysql: Connected to localhost (mailserver)
Nov 14 21:54:44 ns1 postfix/postfix-script[7753]: refreshing the Postfix mail system
Nov 14 21:54:44 ns1 postfix/master[1670]: reload -- version 2.7.0, configuration /etc/postfix
Nov 14 21:54:52 ns1 postfix/trivial-rewrite[7759]: warning: connect to mysql server localhost: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
Nov 14 21:54:52 ns1 postfix/trivial-rewrite[7759]: fatal: mysql:/etc/postfix/mysql-virtual-alias-maps.cf(0,lock|fold_fix): table lookup problem
Nov 14 21:54:53 ns1 postfix/master[1670]: warning: process /usr/lib/postfix/trivial-rewrite pid 7759 exit status 1
Nov 14 21:54:53 ns1 postfix/cleanup[7397]: warning: problem talking to service rewrite: Connection reset by peer
Nov 14 21:54:53 ns1 postfix/master[1670]: warning: /usr/lib/postfix/trivial-rewrite: bad command startup -- throttling
Nov 14 21:54:53 ns1 postfix/smtpd[7071]: warning: problem talking to service rewrite: Success

I tried netstat -ln | grep mysql and it returns

unix 2 [ ACC ] STREAM LISTENING 5817 /var/run/mysqld/mysqld.sock.

The content of /etc/postfix/mysql-virtual-alias-maps.cf file is here:

user = stevejobs
password = apple
hosts = localhost
dbname = mailserver
query = SELECT destination FROM virtual_aliases WHERE source='%s'

Here I tried to change hosts = 127.0.0.1 but it says warning: connect to mysql server 127.0.0.1: Can't connect to MySQL server on '127.0.0.1' (110)

So, I am lost and don't know where else to change in order to solve the problem. Any help would be appreciated highly.

Thank you.