Outlook/Mac 16.105 takes up 70+GB RAM within seconds of starting each

Question

Outlook/Mac 16.105 takes up 70+GB RAM within seconds of starting each

Dr. Guido Rößling 30

I work on a Mac mini (M4 Pro, 24 GB RAM) and run Outlook 16.105 (26011018), "Legacy Outlook". Since about a week ago, whenever I start Outlook, it will allocate 60+, often 70+ GB RAM. Given that my computer does not have anywhere near to this amount of RAM, the computer is hung up.

Any advice on how to fix this issue would be highly welcome. I can run OWA without problem in a browser, but as I have multiple mail accounts, that does not solve my mail issues.

Using the "New Outlook" (which, if I remember correctly, stores the access data on Microsoft Servers) is forbidden by my employer's security policies ("cannot store your password on foreign servers"), so this would also not be a solution.

Fuhge, Robert 0 Reputation points

2026-01-20T15:17:26.4966667+00:00

I do have "New Outlook" Mac 16.105 and I see the same issue - not every time, but I had it three times up to now. Force Quit Outlook from the MacOS (Tahoe 26.2) system popUp brings the Mac back to life...
Dr. Guido Rößling 30 Reputation points

2026-01-20T16:28:02.9333333+00:00

I agree that force quitting revives the Mac. However, the next time I start Outlook, the same happens again - each time...
Fuhge, Robert 0 Reputation points

2026-01-21T09:05:26.4566667+00:00

I just noted that there is 16.105.1 out, probably this helps?
Luke Mason 0 Reputation points

2026-01-21T16:46:44.56+00:00

I've been trying to install 16.105.1 for a few days now and it's failed about 5 times now. It always gets to a few seconds remaining (3 seconds, 5 seconds, etc.) and then just hangs there until it fails.
Jayden-P 20,255 Reputation points Microsoft External Staff Moderator

2026-01-24T14:47:09.5633333+00:00

Hi Luke Mason

Have you tried downloading the app from Microsoft website?

Update history for Office for Mac - Office release notes | Microsoft Learn

Answer accepted by question author

1 additional answer

Your answer

Fuhge, Robert 0 Reputation points

2026-01-20T15:17:26.4966667+00:00

I do have "New Outlook" Mac 16.105 and I see the same issue - not every time, but I had it three times up to now. Force Quit Outlook from the MacOS (Tahoe 26.2) system popUp brings the Mac back to life...
Dr. Guido Rößling 30 Reputation points

2026-01-20T16:28:02.9333333+00:00

I agree that force quitting revives the Mac. However, the next time I start Outlook, the same happens again - each time...
Fuhge, Robert 0 Reputation points

2026-01-21T09:05:26.4566667+00:00

I just noted that there is 16.105.1 out, probably this helps?
Luke Mason 0 Reputation points

2026-01-21T16:46:44.56+00:00

I've been trying to install 16.105.1 for a few days now and it's failed about 5 times now. It always gets to a few seconds remaining (3 seconds, 5 seconds, etc.) and then just hangs there until it fails.
Jayden-P 20,255 Reputation points Microsoft External Staff Moderator

2026-01-24T14:47:09.5633333+00:00

Hi Luke Mason

Have you tried downloading the app from Microsoft website?

Update history for Office for Mac - Office release notes | Microsoft Learn

Answer 1

Jayden-P 20,255 Microsoft External Staff Moderator

Hi @Dr. Guido Rößling

Thank you for reaching out to Microsoft Q&A forum.

May I ask which type of account are you using? (Exchange, POP/IMAP)

Did you download Outlook via App Store or directly from Microsoft website?

If you got the app through App Store, please uninstall it and download it directly from Microsoft web.

Update history for Office for Mac - Office release notes | Microsoft Learn

You can try to install the latest version 16.105 or if you didn't meet this issue before, consider downloading previous version. My recommendation would be version 16.102.x. Also please turn off Auto update in Help > Check for updates > Untick Automatically update.

User's image

I'm currently using the same version and got it from the web; I did not see this behavior. In your Activity Monitor, can you name which one is taking up so much RAM?

For example, Microsoft Outlook Web Content, etc.

Please try downloading from the web and provide more information so I can assist you better.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Jayden-P 20,255 Reputation points Microsoft External Staff Moderator

2026-01-20T07:25:23.4866667+00:00

Hi @Dr. Guido Rößling

Have you checked the provided answer?

Any update would be great.
Dr. Guido Rößling 30 Reputation points

2026-01-22T09:13:01.8266667+00:00

Thank you - as mail notifications are currently problematic due to the Outlook issue, I did not see the answer before. I will try this out once I am back from work at home and will answer then...
Jayden-P 20,255 Reputation points Microsoft External Staff Moderator

2026-01-22T09:18:41.73+00:00

Hi @Dr. Guido Rößling

Thanks for your reply.

Please take your time, I will be here waiting for your reply.
Dr. Guido Rößling 30 Reputation points

2026-01-22T15:34:27.0533333+00:00

I am now back at home and have installed 16.105.1 (26011816). At the moment, it has been running for about 5 minutes and still works, so that is - so far - a drastic improvement. It is a bit too early to really say that this has "resolved" the problem, however.

Regarding another question you had above: the "70+ GB RAM" was the Microsoft Office process, not the Microsoft Office Web Content process.
Jayden-P 20,255 Reputation points Microsoft External Staff Moderator

2026-01-23T07:04:21.4666667+00:00

Hi @Dr. Guido Rößling

Thanks for your reply.

That is a great start, is it still working normally now?

Please feel free to reach out if you need anything else.
Dr. Guido Rößling 30 Reputation points

2026-01-24T10:51:49.3233333+00:00

Yes, it is still working normally (and hopefully will remain that way!). Thank you for the support!
Jayden-P 20,255 Reputation points Microsoft External Staff Moderator

2026-01-24T14:46:10.5466667+00:00

Hi @Dr. Guido Rößling

I'm glad to hear that, if you found my support helpful, please kindly mark my answer as accepted answer.

Warm thanks.

Answer 2

It seems that you are experiencing a significant memory allocation issue with Outlook 16.105 on your Mac. Here are some steps you can take to troubleshoot and potentially resolve the problem:

Disable Add-ins: If you have any add-ins enabled in Outlook, try disabling or uninstalling them. Add-ins can sometimes cause excessive memory usage.
Close Large PST Files: If you have large Outlook data files (.pst) open, consider closing them or reducing the number of folders within those files.
Reset Outlook Preferences: You can try resetting Outlook preferences to default settings, which may help in resolving any configuration issues that could be causing the high memory usage.
Rebuild Outlook Profile: If the issue persists, consider creating a new Outlook profile. This can help if the current profile is corrupted.
Check for Updates: Ensure that you are running the latest version of Outlook. Sometimes, updates can fix bugs that lead to performance issues.
Reinstall Outlook: If none of the above solutions work, you might want to consider uninstalling and then reinstalling Outlook to ensure that there are no corrupted files.

If the problem continues after trying these steps, it may be beneficial to reach out to Microsoft Support for further assistance specific to your version of Outlook on Mac.

References:

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Outlook/Mac 16.105 takes up 70+GB RAM within seconds of starting each

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