Which list setting to stop this

[southmartin]

Hi

Since adding magicspam to plesk, we've had a few people experience bouncebacks when trying to send mail.
Can anyone tell me which list setting to DISABLE to ensure this doesn't happen? - here's an example of two of the bounces

There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<robinsons-cpq.robinsonslondon.local #5.5.0 smtp;550-Your message was rejected by this system and was not delivered.>

550-Your message was rejected by this system and was not delivered.
550-Reason: Your IP address [195.103.143.50] appears not to be an email
server. 550-Protection provided by: MagicSpam 1.0.4-6.1

Many thanks

[magicspam]

The first message does not provide enough information for us to be able to determine which rule is responsible for blocking that connection.

The message for 195.103.143.50 is because the reverse DNS entry for that IP is a dynamic-style address. Properly configured mail servers should have a reverse DNS entry that resolves to their domain, rather than their upstream provider's domain. The ideal solution to this issue is to have the sender change their reverse DNS entry to comply with the best practices. Turning off the rule will likely open you up to more spam, as many spam hosts are compromised home computers that are likely to have similar hostnames. However, if you are intent on disabling the rule, it is "Block Mail Servers on Dynamic/Dial-up Addresses".