PHP mail() is selective with external domains

[rvk]

I've seen a bunch of posts on this issue but none seem to have a definitive solution.

I am using the php mail() function to send a confirmation to users who fill out my contact form. The function sends to some domains and not others.....what's the deal?

Sends to:
All internal domains
gmail.com

Won't send to:
yahoo.com
telus.net

Thanks for your time,
R

[rvk]

turns out this is a spam filter problem. Yahoo has better filters than gmail

R

[rvk]

I did some more testing on this issue and discovered the following:

I used the same php mail() script at IXwebhosting.com and hostrocket.com; ALL emails reached their destination and NONE were flagged as spam. This same script used with powweb.com resulted in only 1 delivery out 20.

Seems there's something amiss at powweb

R

[HalfaBee]

Make sure the From and Reply to headers match a smtp user in ops that is the "owner" of the email addr