I downloaded an app from Zhaopin Recruitment. When I filled in the information and saved it, I was reminded that this email address has been used. This means that someone else has used your email address to register.

Many people should know that through settings, a Gmail username can be changed into many "aliases" for different purposes. Of course, this is not Google's original intention, but these functions do bring some convenience to our use.

E-mail registration:

As for changing the suffix, because Gmail’s trademark in some countries has not been negotiated before, the Gmail trademark cannot be used and I have to use Google Mail. This is easy to understand. (It seems that all global trademarks have been negotiated now). If it's just for registration, just change it when filling in Gmail. There is no need to go to Gmail settings, different email addresses will appear in the same inbox.