Outlook 2016 for Mac, Outlook for Mac for Office 365; In this article. Original KB number: 2800895. We do not recommend that you change the default location of your Profile folder for Microsoft Outlook 2016 for Mac, or your Identity folder for Microsoft Outlook for Mac 2011 to an external hard disk or to a network. I have had two cases where different users using Outlook 2011 for Mac have hit a limitation where they receive a message that they cannot send because of the message size. They are way below the exchange sending restriction. They can send the same message through OWA just not Outlook 2011 for Mac.

It's I/O related. 15 GB is a LOT of data to have to sling around. The bigger the OST gets, the longer it will take Outlook to wrestle it into submission each time Outlook opens. Imagine opening a 15 GB PowerPoint of Photoshop file. It's going to take a minute...or three.

Outlook Message Size Limit

As for the problem going away with the move to Exchange online, it won't make a difference as long as you are running Outlook in cached mode with 15 GB mailboxes. That's the real issue. Email servers were not designed to be file repositories and moving the mailboxes offsite will only exacerbate the I/O issue since your internet pipe is not likely to be as big as your LAN pipes.

Outlook Size Limit For Attachments

So your real issue is mailbox size. There are lots of ways to approach the problem but that's a whole other discussion.

Find Size Limit Outlook For Macbook Air

Oh, and the default limit of OST's (and PST's) under Outlook 2013 and 2016 is 20 GB but just because you CAN make a 20 GB OST doesn't mean you SHOULD (see previous discussion about large files).

Outlook 2013 Mailbox Size Limit

For example, if you customize your settings for a 100 MB maximum message size, you can send messages no larger than 75 MB. I get the same message in the OWA as I do in Outlook. The file is too large. The limit is 27mb. Your message is 28mb. This problem may occur if you have folders that exceed the limit for the number of items per folder or if you have too many folders total. The limits for Outlook 2019, Outlook 2016, Outlook 2013, and Outlook 2010 are as follows: 100,000 items per folder; 5,000 items per Calendar folder; Resolution. What's the file attachment size limit in Outlook.com? The attachment size limit for files is 34 MB. You can also share a file from OneDrive. This way, your recipients can receive larger files and collaborate on it in real time. The attachment size limit for OneDrive files is 2GB. Read more about how to Attach files in Outlook.