No problemo, as Arnie would say!
Now, as far as your issue is concerned, I can't remember what was suggested and/or what you tried in the other threads you had started about this issue. But I'll make some anyway (sorry if they were mentioned before).
1. Have you ever performed disk cleanup/maintenance/repairs?
2. Are you making a backup to an external device? And if so, what software are you using?
3. When did this start happening?
4. Not sure if you have some adware/malware that is contributing to the issue, but you could download, install, and run the excellent freeware program Malwarebytes, available form here:
https://www.malwarebytes.com/mac/
Another good one is ClamXav, available from here:
https://www.clamxav.com/
You can use in in demo mode for 30 days.
5. Maybe you should try another EMail program. Thunderbird is a decent one, and it's free. You can get it form here:
https://www.mozilla.org/en-US/thunderbird/
I would say that if AT&T can't help you, and if the issue persists especially after using Thunderbird, then maybe you need to do a clean, fresh installation of El Capitan.