Error : 111 Can’t open SMTP stream – SquirrelMail

                       Error : 111 Can’t open SMTP stream – SquirrelMail
ERROR:
Message not sent. Server replied:
Connection refused
111 Can’t open SMTP stream.

Resolution :
One common problem people have is an incorrectly setup mail system. Here is a list of rules that must be followed:

1) Hostname must not match any domain that is being used on the system. Use hostname as server.domain.com.
2) You must make sure that you add the A record for server.domain.com so that it resolves.
3) The hostname must be in the /etc/virtual/domains file.
4) The hostname must *not* be in the /etc/virtual/domainowners file.
5) The hostname must resolve. If not, add the required A records to the dns zone such that it does.
6) The directory /etc/virtual/hostname must exist.. It must not contain any files.
7) Any domains that you want to use for email must be in both the /etc/virtual/domains file and the /etc/virtual/domainowners file. The directory /etc/virtual/domain.com must exist and the files /etc/virtual/domain.com/passwd and /etc/virtual/domain.com/aliases exist.
8 ) File permissions for virtual pop inboxes should be :
/var/spool/virtual/domain.com 770 username:mail
/var/spool/virtual/domain.com/* 660 username:mail
9)Ensure your hostname does not contain any upper case letters.
10) Make sure that your main server IP has a reverse lookup on it.
The other easy step to resolve this issue is editing /etc/exim.conf where it says
#daemon_smtp_ports = 25 : 587
daemon_smtp_ports = 25
make it
daemon_smtp_ports = 25 : 587
#daemon_smtp_ports = 25

Hope this help you get your issue resolved…