I'm working on a client's website and they are not getting messages from the site anymore.
I've found that no mail will go to an email address ending in @gmail.com, I can send mail just fine to anyone within my company that has an email with a custom domain. But a Gmail inbox the messages never even seem to make get close. They're not in spam, not in promotions, nowhere.
I've installed WP mail log, and see no errors on the site. It doesn't appear to be an SMTP issue as I can send messages just fine.
I know this is not explicitly a WordPress issue but I've run out of ideas and options to try so if anyone has encountered this and has any ideas it would be appreciated.