SMTP TO: vs MIME TO:

Hi,

I'm trying to track down what might be causing my mail to one recipient (on an Exchange Server), ending up in their spam folder. I know that one of the issues is likely that I am not using SPF records at this time. I'm not too worried about that at the moment.

I'm more concerned or confused about another alert they received when checking why it was in the spambox...

"03/07/07 13:23:04","AntiSpam Header
checking","user@domain.ca","otheruser@otherdomain.ca","Re:
subject","Moved to Exchange folder Inbox/SPAM Email","Email has
different SMTP TO: and MIME TO: fields in the email addresses"

... any idea why that would be?

If it matters, user@domain.ca is me and is a normal account and is the acccount I am also sending from. otherdomain.ca is an account on my server where I am hosting web only. The dns zone is on their server. otherdomain.ca is not listed in /etc/localdomains and is listed in /etc/remotedomains. There is no dns zone file for otherdomain.ca on my server.

Thanks for any ideas,
verdon