Using HTTPS links should resolve the issue.
If you face the problem still, in that case, then it is a challenging problem to debug. The following list might contain the reason:
- Using the HTTP link
- No DKIM
- No SPF
- No DMARC
- Verifying your domain (click base url) at postmaster.google.com
- Using public url shorteners like bit.ly
- The IP pool AWS SES is using to send your emails might have a low reputation
Last update: November 29, 2020