Avast blocks some emails on two computers, and creates duplicates on another

[REDACTED]

Normally I would just change A/V programs, however the users are adamant about keeping avast.
The user with the blocked emails is using Windows 10 and Outlook 2007. The mail is from the ISP Cox and is using their standard POP settings. Now is there a way to see the headers or other information for emails that Avast is blocking? She doesn't  want to switch to IMAP.
The user getting Duplicate emails is using Win 10 and outlook 2013.She is using POP as well.
Any suggestions on where to start would be appreciated.  I tried the obvious things like reloading Avast and it made no difference.

[Pondus]

The user getting Duplicate emails is using Win 10 and outlook 2013.She is using POP as well.

This seems to be a outlook issue, if you google it there is a ton of info to find

The user with the blocked emails is using Windows 10 and Outlook 2007.

Does it work if you turn off mail shield?

[REDACTED]

I had a similar issue several years ago. It was nothing to do with Avast. I set up an Outlook Express POP redirect desktop icon to load emails for an account set up by my internet service provider. Everything was fine until the ISP switched from using Google to Yahoo. Immediately everything went to the desktop in triplicate and I couldn't access the account on the normal web page or on any other computer. I had to disconnect the Outlook Express POP redirect and once I did that everything was fine. I suspect the OP's problem is related. I doubt replacing Avast with another anti-virus product will help.

[REDACTED]

I had a similar issue several years ago. It was nothing to do with Avast. I set up an Outlook Express POP redirect desktop icon to load emails for an account set up by my internet service provider. Everything was fine until the ISP switched from using Google to Yahoo. Immediately everything went to the desktop in triplicate and I couldn't access the account on the normal web page or on any other computer. I had to disconnect the Outlook Express POP redirect and once I did that everything was fine. I suspect the OP's problem is related. I doubt replacing Avast with another anti-virus product will help.

I had the email hosting company help me set up outlook exactly to what they require. Still getting duplicates frequently. I should make sure there is no forwarding turned on somewhere. That is a good point.

I currently have the mail filter off, and will test for a day or two in regards to the blocking problem.

PS I hate the stupid unreadable verification.