Important emails always going to junk

Hi,

My website regularly receives enquiries via a form, all of which should goto my inbox (and they did for the first 4.5 years). All of a sudden all of these emails are going to junk which is a bit of an issue since they require quick responses ideally.

I've flagged them as safe, added to safe sender list and even created rule for all emails from this address Togo my inbox, none of which has worked. Absolutely nothing has changed our end.

very frustrating if anyone has any advice