Automated email sending system - Spam Weight

Question

Good day,

We have developed a system that send out automated mails to our clients, with a pdf attachment. Some of the clients have mentioned that the mails are being picked up as spam, and the IT guys say that the mails have a high spam confidence

As mentioned the headers from your system include a 2.0 TotalSpamWeight, while it should be < 0.

What should I be looking at to change this?

I am using Delphi 2010, indy 10's tidSMtp component to make the mails. The body is in html, and the images in the body are externally hosted.

Please advise

Answer 1

Ask the IT guys which rules are being triggered.

Answer 2

This might not be Delphi-related. Is the sender of the email from the same domain that sends the email? You could ask your client to send you the headers of the message that they received as spam, then examine those headers. The TotalSpamWeight is calculated by some anti-spamtool, possibly from SmarterTools or SpamAssassin and might just be related by some keywords in your email. The word "Viagra", for example, would trigger a lot of anti-spam filters, even if you mention it in such an innocent way as I just did...
Oh, those externally linked images could be what triggers them! Many spammers use them to track emails and tend to add a special code to each image which would confirm if someone's email address is real or not. If the image is downloaded, they've confirmed the email address. If not... Well, this trick is why external images would trigger emails as spam. Especially when combined with some other keywords.