SMTPmail from asp.net page going to Junk Email

I have a page that generates an automated email message. Until the last several weeks, this has worked as I expected. Now the mail gets filtered into my Junk email. After lots of testing I discovered that only messages that contaion http: links are filtered as junk. ( I can modify this page and take out the http://www.davidson.edu, and the mail is delivered to my inbox. I have my junk email set to "high". Setting it to low solves the problem, but I think that may just mask the problem. Another interesting fact is that it is not ALL mail containing http: links that gets sent to junk. I forgot my password for this site, and when I received the mail telling me my username and password, it contained a link to the login page and it was delivered to my inbox, not junk mail.

Is there some header or mime-type that I'm missing?

Here's my code:

Dim mailmsg as new MailMessage()
mailmsg.body="here is a link http://www.davidson.edu/"
mailmsg.from = "someuser@dotnet.itags.org.davidson.edu"
mailmsg.to = recipient
mailmsg.Headers.Add("Reply-To", "someuser@dotnet.itags.org.davidson.edu")
mailmsg.subject = "subject"
smtpmail.smtpserver="localhost"
smtpmail.send(mailmsg)I have dealt with this issue before. Mail gets rated by something (ie Barricuda, of some piece of mail evaluation software) Then the mail gets graded in points, depending on the amount points it gets will determine whether or not it gets flagged as junk. For instance you get points for not having your MIME header set correctly as well as not having a defined content type etc.