I have a similar problem due to the whole "gmail.com" vs. "googlemail.com" thing that came about in Europe in the earlier days of Gmail.
When I got my gmail account, Google gave me a "googlemail.com" address, due to a pre-existing trademark in Europe. These days the "gmail.com" suffix works for my account, but I've already set everything up with the "googlemail.com" form and saw no reason to switch. Sometime in 2016, someone started using the "gmail.com" version to sign up for stuff, and I repeatedly nearly fell for this exact problem... It's made more difficult by the fact that Google clearly _want_ me to use the "gmail.com" form, and refer to it by that address in many places, despite me opting to use the long form in settings.
I don't think the person using my email address is being malicious, I think it's by mistake, but I have no means to contact him to fix the problem.
When I got my gmail account, Google gave me a "googlemail.com" address, due to a pre-existing trademark in Europe. These days the "gmail.com" suffix works for my account, but I've already set everything up with the "googlemail.com" form and saw no reason to switch. Sometime in 2016, someone started using the "gmail.com" version to sign up for stuff, and I repeatedly nearly fell for this exact problem... It's made more difficult by the fact that Google clearly _want_ me to use the "gmail.com" form, and refer to it by that address in many places, despite me opting to use the long form in settings.
I don't think the person using my email address is being malicious, I think it's by mistake, but I have no means to contact him to fix the problem.