Spam filter troubles

Hi,

We have been having trouble emailing someone who we believe uses PlusNet email. Every time we try to send an email to this person, it is rejected with this message:

avasin16.plus.net gave this error:
Spam Message Rejected

We aren't on any RBLs, we have a valid SPF record, and even plain text emails get blocked so we aren't sure why this is happening. The IP address of the mail server is 77.243.188.230.

All of the help channels that we go through seem to be for customers only so we're a bit stuck. Can anyone help please?

Hi,

Would you be able to PM the e-mail address you're trying to e-mail and I'll take a look for you?

PM sent. Thanks for looking in to this for us!