What's Causing This Error
SendGrid doesn't really send emails to the SPAM folder. Instead, it is up to the receiver's spam filters in the mail delivery flow.
A significant proportion of mails are tagged as spam for one of the reasons listed below.
- People are labeling emails as spam because they are not adequately verified.
- The message is not authenticated properly.
- An email comes from an IP address that is blacklisted (perhaps SendGrid's).
- Your email contains known phishing techniques (coincidentally or not).
Here's How To Resolve It
- Try sending a message to yourself and open the message headers, then look for entries like the one below:
Received: from xxxxxxxxx.com (xxxxxxx.com [xxx.xx.xxx.xx])
by xxxx.com with SMTPS id ##############
The IP address within  is the IP address of the sending server. First, check a public blacklist, like spamhaus, to verify whether it's blacklisted, then report any matches to SendGrid.
- Build your own email list.
- Provide a double opt-in.
- Authenticate your email with SPF, DKIM, DMARC, and BIMI.
- Clean up your email list regularly.
- Avoid deny lists and monitor your reputation.
- Monitor your email engagement metrics.