Well...this problem went away. Before this post, I rebooted, and then did a reboot with battery removal. Neither of these had any effect. I spoke to TM customer service, but the person I spoke with really had no idea. She passed my issue along for additional research, and I never heard anything back from that. The phone began to receive email again about an hour after the service call and reboots.
I did not take any action with my email service providers, or with my accounts on the phone.
I do not know the cause, and now not the solution, but it works flawlessly again.
Thanks for the responses.