Gmail/Hotmail Flag email as spam

Question

I have a simple .NET app that is sending out email using SMTPClient.

I am sending from an authenticated account on the local server with an SPF record, and the host (gogrid) is unsure what else they can do to solve the problem.

Any email from my simple app is flagged as spam, but any other email sent using that smtp server, or through squirrelmail, etc, comes through fine. So there must be something that apps like squirrelmail are doing that I'm missing.

Has anyone else encountered and/or solved this problem?

Answer 1

Compare the MIME output of the two emails (squirellmail vs SmtpClient), using the Show original command in Gmail, and post the differences here.

Also, check SmtpClient's SMTP settings.

Answer 2

Likely you are missing your encoding in your MIME info, or have your return email not set or different to make it look fake. Without seeing what parameters you are/are not filling out it is hard to say.

SLaks answer is good step as well.

Considering that other email from the server is not being flagged, a blacklist or missing parameters there is unlikely.

Answer 3

You should consider signing your messages using dkim.

see http://www.dkim.org/

or

http://en.wikipedia.org/wiki/DomainKeys%5FIdentified%5FMail

regarding your spam vs. clean email content, look at the x-spam-status field in the "spam" message. You can try to figure out what the problem is by checking the tests that were flagged against the spamassassin descriptions:

http://spamassassin.apache.org/tests%5F3%5F2%5Fx.html

Answer 4

Try sending a header with the PHP mail() function that specifies the 'from' address as being a valid email address on your server. That is to say: create an email account on your webserver for 'sending' the emails, then have the PHP script report the messages you send as coming from that account. I do this with my mailer and haven't had any problems with spam filtering.