Part of the problem is a feature of gmail that I really like, but causes some issues.
If you open a gmail account of say
[email protected] you actually opened an account called alsmith, google doesn't care about the periods, and now you own hundreds of different email addresses. You own every permutation of alsmith with periods in it.
[email protected]
[email protected]
[email protected]
etc...
This is great because someone can't try to be you and trick someone by creating an account that looks similar. Unfortunately it also means people open up Twitter or Facebook accounts with those other email addresses and Twitter or Facebook don't recognize it as a duplicate of the one you normally use. When that happens I immediately login into those accounts and change the email address. I don't want getting spammed with their feeds.