Have you been blacklisted? Is your email being rejected by mailservers?

The best thing you can do to prevent your mail server being blacklisted is to make sure that your passwords are strong.
Strong means longer than 16 random alpha-numeric and non-alphanumeric characters.
Alternatively, you can use pass phrases with numbers and punctuation.

If you suspect that your server has been sending spam (usually because of bounced emails), you can check using an online blacklist tool:
http://mxtoolbox.com/blacklists.aspx

If your server is sending spam you need to reset all mailbox passwords.
The usual reason that servers become blacklisted is due to weak passwords which have been brute-forced  (guessed) by spammers. They then use these compromised accounts to send thousands of spam messages.

If resetting the passwords doesn't stem the flow of spam, the source of the spam (usually an insecure web form) needs to be identified.

You can use your system's method of viewing emails that are in the queue to see whether a local domain name is connected with the spam emails.

If you are unable to identify the source of the spam you can open a CWCS Special Request via our support site, https://support.cwcs.co.uk/, and one of our Technical Analysts will trace the source of the spam.