User level email filter rules are not being enforced

Hi all,

I've been lurking for a while and I can't seem to find anyone who has faced the same issue.

I basically have a set of users with email addresses on our domain, and I don't want these users to send email to recipients who are outside of our domain.

Essentially I want to only allow these users (in our domain, say "blah.com") to send email to those of "@blah.com", and not outside this.

I had a think about it and I came across the "user level filtering" tool. I set out to test by going to my email in the list of users, and creating a new rule.

I created a rule to "fail with message" whenever the recipient field does not contain "@blah.com".

I test this filter using the Filter Test section, after saving changes. The filter test seems to report that it works.

Now...here comes the punchline:
All our users are using an external email client to access their email on our domain, and are not accessing email using cpanel at all. The major email client being used is..Gmail. The next being their iPhones.

I can confirm right now that the user level filters I created are not being enforced when sending and receiving email via Gmail or iPhone. I wouldn't expect this to occur, since the clients are configured to send via our SMTP server (say, smtp.blah.com).

I have no idea why this is. Aren't these email filters applied to our SMTP server? So it shouldn't matter what our email client is? Unless the filters only work if the users are using email through cpanel..

Very strange problem. Would appreciate some guidance.

Cheers

 

Damn, what a pity. I got excited when I saw the rules one can create under these filters.

I suppose there's no other way to achieve rules on outgoing mail?