Lost emails in att.net account


New Email
I went to check my email tonight, and there are no emails from before November 8th! There were emails from before that date in there this morning. This is not the first time that happened. The last time, emails beyond a certain date disappeared, so I thought perhaps att.net automatically deletes emails beyond a certain time frame, or perhaps restricts users to a certain number of emails in the box.

The emails left in my box are from November 8th to present, and there are 72 emails now. Before this evening, there over a hundred in there, but I don't remember how many.

Does anyone know if att.net automatically deletes emails or if there is a way to get them back? Thank you.