Why did Outlook stop receiving inbound IMAP e mail?

I have Outlook 2007 and two different e mail addresses, both using Google e mail accounts, and both are IMAP accounts. They are on the same pc, just two different e mail addresses on the same Outlook. I will call one account-a, the other account-b herein.

Both were set up over 5 months ago and worked well until 2 days ago.

Currently one of the accounts, account-b works properly. This suggest that the pc, my network etc are all performing properly.

The other account, account-a, does not display new e mail. I can send out e mail without any issue.

I can go to the Google e mail on a web browser and see the e mail is available so I know new e mail is making it to the Google server; it is just not going from Google server to my Outlook.

I have checked all the e mail configurations for servers, port numbers, encryption, etc and they are proper. I have checked the file size and even made sure to purge deleted items, which made no difference.

I made NO changes to any settings so there is no known assignable cause for this apparent failure.

It is acting like something is just blocking e mail for account-a. Account-b, which has the same domain but different account name only, works properly; both use the same e mail server domain which is then forwarded to the Google server due to MX record change. The MX record change is common to all on the domain; other users on the domain, who have POP or IMAP servers, whichever they wished to set up, report no issue.

I have run virus scans using different antiviruses and nothing was found on the pc that receives the e mail.

The entire PST file is about 170 KB, I am told that if it gets to about 20 GB I would have a size issue that could stop receipt.

It seems like the issue is an Outlook issue since all on the Google IMAP server seems to behave. The term "Outlook issue" as I use it could well be a configuration, setting, etc.

I have it set to send down only the intial info, not the entire e mail as is common to IMAP and this is not the matter; nothing is seen coming down.

I would appreciate any thoughts anyone may have.