Outlook suddenly stopped receiving messages..

[#1]

Suddenly started getting error messages (0x800CCC90) and unable to receive emails as from yesterday.... Nothing changed by me.... Any ideas?

[#2]

Which version?

https://office-watch.com/2017/the-many-faces-of-microsoft-outlook/

[#3]

Outlook 2016

[#4]

Stab in the dark.

Have you tried disabling all rules?

[#5]

Only had the one rule, which I have disabled.... Got 3 messages through, but then got the error message again... Any more stabs?   

[#6]

Do you have more than one mailbox collection account set up?

[#7]

Yes.... However, a new Mail icon appeared on my front page after a recent update. I wonder if this is relevant? 

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[#8]

The error you experienced has been blamed on outlook trying to collect mail from multiple POP3 accounts simultaneously. Do you still get the error if you try just one?

To do this,:
click the Send/Receive menu item (top row)
click the Inbox for one of your accounts on the left
click Update Folder on the ribbon.