why are my mails being sent to junk folder?

"Short answer, check if your IP is blacklisted. Lots of places to do this. www.mxtoolbox.com works for me. no relation or affiliation.

Longer answer, your mail client might not like the content of the test messages you're sending. Or it's seeing so many of them that it thinks it's getting spammed.

If you're not on a blacklist then set up a new email account somewhere else and try sending one message there from your server to see if that gets through."