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BrittanyN's avatar
BrittanyN
Copper Contributor
Jan 09, 2026

Classic Outlook Keeps "Not Responding" and freezing

Hi there,   I tried to scour for something similar, but I couldn't find anything and/or it didn't work - so here I am - hopefully someone can help.  Okay the facts - I use Classic Outlook (CO movi...
classic outlook
outlook for windows
RobertSparnaaij's avatar
RobertSparnaaij
MVP
Jan 10, 2026

Are your corporate accounts on-premises Exchange accounts or hosted at Microsoft 365?
Do you have Cached Exchange Mode enabled for these accounts? If not, make sure that you do and to cache it for at least 3 months.

Does this happen when you are inside the corporate network (on location) as well as when you are working from home (if possible)?

Which COM Add-ins and which web add-ins do you have installed for your corporate mailboxes?

Additionally see; Outlook doesn’t start, crashes or shows Not Responding - Robert 365

  • BrittanyN's avatar
    BrittanyN
    Copper Contributor
    Jan 12, 2026

    Exchange accounts. - It was enabled but it was set to a year so I lowered it to 3 months as suggested. 
    Only at work as I have not checked it on my home computer lately. All COM add-ins are off at the moment while I've been troubleshooting. 

    After I played with it a bit more on Friday, it seems it may be linked to html in the emails. I had the 1 account running okay within an email thread with no html - not perfect but it was better. 
    Still at a loss at the moment.  

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