My gmail address is a short one, based on my name, and likely similar to many others' names too. For a long time now people have used my email address to sign up to all sorts of stuff. I'm pretty sure it's not purposely malicious... I mean the only way to exploit that would be to have control over google's authoritative DNS servers. But, I often wonder if there is something I am missing. I don't think so, but would be curious to hear others' opinions.
Also, you'd be surprised at how many sites have auth bypass issues when accessed via links in emails. I recently got an email from a hotel in Florida where someone had used my email address to book a room. Using a link in the email, I was able to access the booking details, and could have cancelled, or added a further couple of nights with no further authentication.
As you have the access to that email account then I suspect that the only ones with something to worry about would be those which are mistakenly using your email address of which they have no access. I'd guess it regularly happens.
I have the same problem.
The person using my email had the same email address except it had a . between two of the characters.
Got a fright a few times saying I signed up for something.
Try again James
(hint... look over there <<---- )
Apparently Gmail ignores dots in the account name.
Also @gmail.com was merged with @googlemail.com and possibly a few others, so more potential for duplication, never mind people just typing incorrectly.
I keep telling people that your email address is like the return address written on an envelope. It's visible and anyone can use it on their envelopes, stuff using that address will get delivered to you rather than them.