You are trying to send an email in C# from your website (using Exchange as the email server), but you get the error message
Mailbox unavailable. The server response was: 5.7.1 Message rejected as spam by Content Filtering.
whenever you send the email. It is clearly not spam.
You are triggering a spam filter based on the number of words and characthers in the sample email you’re sending.
You should increase the number of words in the body of your email by five or more. It’s strange, but it works.
||Written By Steve French|