According to PLESK, the point of the Mail message submission feature is to “protect your server against unauthorized mail relaying or injection of unsolicited bulk mail.”, So in other words, They mean security through obscurity, or in other words, if the hacker does not know that the port is 587 rather than 25 then they will not be able to relay mail right ?
security through obscurity is in a few words “A system relying on security through obscurity may have theoretical or actual security vulnerabilities, but its owners or designers believe that the flaws are not known, and that attackers are unlikely to find them.”
Well, i don’t think so, surely not when PLESK hard codes a port !
You see, Mail span software evolves daily, and when you popularise a port, it is probably on the checklist of spammer software.
So how do you stop the spam ? I personally implement a system to limit the amount of email a Domain name can send and requier authentication to send mail.
So, not to go off topic, the Mail Message submission feature does have a use to me, Even though it is not rocket science to open extra ports for mail, This feature is rather useful for users who have there port 25 blocked for example.
In Jordan, Most ISPs block port 25 to reduce spam, as an expert i have no clue how they intend to stop spam by blocking port 25, They can’t be serious, Spammers are power users and they know how to overcome the Port 25 issue, and there are not many servers on the internet that are open relays are there ?
Anyway, i am not here to critisize them either, the point is, You can always open alternative ports for your users (Any port you wish) and instruct them to use it, and plesk makes it easier with a single click.
As i write, A PLESK 8.6 Windows machine displays the message next to Switch on message submission, i will let you know about this feature in Plesk 9 and if it is available and what workarounds exist for this as soon as i get PLESK 9