Cell phone stolen, how do I get access to my email?

Hi @HainesLG! We completely understand your concern regarding accessing your email, and would like to help. Let's get the assistance you require.

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@HainesLG  Can't you login to your email via the AT&T website? Just use the credentials that you use on your phone.

I have tried to log in on the website multiple times, but it always asks to verify with my phone number. 

Then you will probably have to contact support via the Contact Us link and see if they can get you access. However, if your phone or phone data was not secured (auto login to various apps) then losing access to your email might be the least of your problems. Have you remotely been able to lock or erase your phone using something similar to Apple's Find My Phone app?