Here’s an excellent post on the problem with using Verizon email. It clearly explains the difference between IMAP and POP3. I was surprised to learn that Verizon STILL doesn’t support IMAP. Apparently they do not want to incur the storage costs associated with mail being stored on their server rather than downloaded.
If you like to receive mail on multiple devices (and who doesn’t these days?) don’t use Verizon’s email service. Even if you only receive mail on one device, if you download it to that device, either deliberately or accidentally, you will need to set up a backup of it or risk losing all your mail. Leave that headache to your mail provider and use an email provider that supports IMAP.