Here is a set of online tools you can use to check your email server configuration:

Google Admin Toolbox Check MX

Mail delivery check

• https://mail-tester.com

• https://www.mailgenius.com

• https://www.experte.com/spam-checker - "...it uses well-known spam filters and blacklists to check the spam score of a mail. But in addition, it also checks whether Gmail classifies the email as spam and into which inbox the mail is placed." - Janis von Bleichert, Experte.com

• https://multirbl.valli.org/

Requires login:

• https://unspam.email/

Check SPAM score of your email message (copy/paste)

• https://spamcheck.postmarkapp.com/

Additional services

• https://testmail.app/
• https://www.emailonacid.com/

New:

• https://kickbox.com/email-spam-tester/

Updates

• 2022-06-01 Wednesday 18:49:45 - added https://www.experte.com/spam-checker