I am trying to create a newsletter for our business.

The last few days have been spent testing, and one of things I have noticed is that MSN seemingly randomly filters out some of my test messages.

This is super-frustrating.

I like the PEAR Mail MIME-package, and have been using that. I may send one email from one of our servers, resulting in the message getting through, and in the next minute, the same message sent from our other server ends up in the junk folder. Then if I add an attachment to the email, and the same message passes though the filter from the server that was previously blocked. I think. What the ####? Is this like throwing a dice, without me having any control over what is trash, and what isn't?

I have sent email from several servers, all of which are shared. But I am unsure this is the problem. The problem is that it is seemingly random how MSN filters email. Some emails get through, and some other don't for seemingly irrational reasons.

I am running out of ideas, but I am not giving up. Therefore I am writing to you for HARDCORE technical info on how MSN filters spam.