It is probably not an issue with the email script itself. What is the TO address? Are you saying it doesn't arrive if one of those email addresses are simply in the email body?
Most likely the email is being spam blocked. Those servers have more strict standards for spam checking. There are a few reasons why it could be blocked:
1) Your email server is on an email blacklist
2) Your email content is too spammy (uses keywords that they think look like junk mail)
3) You need SPF records on your server or need DKIM set up on your server
Can I see a copy of the page and the email include files it uses? I can see if I can spot the problem.
Did this help? Tips are appreciated...
