[chad_c]

Another explanation is the address changes Google introduced. I’m not sure when, but my [e-mail] became addressable as [e-mail]. Someone else originally created [e-mail] and I get their emails.

[ridaj]

Periods have always been discarded by Gmail when routing mail, as well as signing in. If you own [e-mail], you've owned [e-mail] all along, as well as [e-mail] for that matter.

You're getting that other person's email because someone has the wrong address for them.