I have been having a lot of problems with my host and mod_security.

My host keeps on saying that issues with permissions are causing certain emails to be blocked from being sent out. I have had them make changes and this fixed the issues for a time, but after a few weeks the problem is back again.

Can anyone tell me exactly what mod_security does and how it is enabled by the server when emails are attempted to be sent out. These emails are just basic emails, some have attachments some are just a few lines of text, some have web links or email addresses. But it seems to be random when the mod_security is enabled again to stop the emails going out. When moments before other similar emails were sent without any issues.