Hi there,
Thank you for getting in touch with the community. One thing that can sometimes work is sending an email to yourself and marking it as not spam. Also, in Gmail, you can click the three dots on the message, select "show original," and check for any issues listed there. After a few accounts mark it as not spam, it should start delivering to the inbox. Another thing to check is if your IP is on any RBL blacklists. You can check that on mxtoolbox.
Best regards,
Zach Sylvester
Software Developer
SmarterTools Inc.
www.smartertools.com