I can't explain why email from my mail command from my VM kept landing on my Spam folder.

echo 'test' | mail -s 'test' jdeo@gmail.com

Noticed

• I've noticed that on Linode VMs, mail is not landing on my Spam folder.
• When I am on Digital Ocean VMs, emails kept landing on my Spam folder.

I have the same settings.

What should I check further ? How do I make my mail not land in the spam folder ?