Weird sendmail issue?

[csousley]

I have a web form that sends mail to a bunch of people, no big deal. The problem is there are a few people who don't receive the mail. These people are on the list and can receive the mail if I forward it off to them, but otherwise nothing. The script works fine for everyone else. The issue is happening for a few msn customers and one local guy who's mail server is hosted who knows where.

I don't know if using sendmail puts anything in the header that would make msn think that this mail is spam and then kill it or what the deal is. Anyone run into this before? Thanks.

[theeper]

Some mail hosts won't accept mail if the sending hostname cannot be reverse mapped. Check with your ISP and make sure it does. If you are on a virtual host, it is likely that it will not reverse properly at all. In that case, you may need to forward your mail from the server to a known reversable host, then send it to your customers from there.