Issues related to setting up and using your mailserver and mail clients-Using an external Mailserver – If you wish to use a remote Mailserver, a few changes will need to be made.
1) Go to User Panel -> domain.com -> MX Records
There should be an important option for “Local Mail Server“. Now Uncheck that option.
2) You will need to change the MX dns record to point to the external mailserver. Remove the “mail” MX record and add “other.domain.com.” as the new MX record is where that is the domain of the other server.
** If there you do not have the MX Records menu in your DirectAdmin User Level login, then you should ask your hosting provider to enable the DNS Control option for your account.
How to setup the Mail System
One common problem for people have is an incorrectly setup mail system. Here is a list of rules that must be followed:
1) host-name must not match any domain that is being used on any system.
For Example, if you have a domain called domain.com and you want to receive the mail on email@example.com, you must *not* set your host-name to domain.com. We are recommend you using server.domain.com instead.
You must be make sure that you add the A record for server.domain.com so that it resolves.
2) The host-name must be in the /etc/virtual/domains file.
3) The host-name must *not* be in the /etc/virtual/domainowners file.
4) The host-name must resolve. If not, add the required A records to the dns zone such that it does.
5) The directory /etc/virtual/hostname must exist.. (eg: /etc/virtual/server.domain.com). It must not contain any files.
6) Any domains that you would use for email (eg: domain.com) 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.
7) File permissions for virtual pop inboxes should be (not applicable with Dovecot/Maildir):
/var/spool/virtual/domain.com 770 username:mail
/var/spool/virtual/domain.com/* 660 username:mail
If you would have made any changes to you /etc/exim.conf file and require a fresh copy
8) Ensure your host-name does not contain any upper case letters.
9) Make sure that your main server IP has a reverse lookup on it.