Email and Microsoft 365
What to do when your mailbox is full
Outlook warns that your mailbox is almost full. If you ignore it, email eventually stops arriving.
1 min readWhat to do if
The short version
When a mailbox reaches its limit, it stops sending and then stops receiving. Here is how to clear space and keep it clear.
What happens
Every Microsoft 365 mailbox has a size limit set by its license. As it fills, Outlook shows warnings. Past a certain point you can no longer send. Then you stop receiving, and senders get a message that your mailbox is full, which can mean lost business.
Clear space now
- Empty Deleted Items and Junk Email. Deleted messages still count until those folders are emptied.
- Find the big messages. In Outlook, search the mailbox and sort by size, or search for large messages. A handful of messages with big attachments often take up more space than thousands of ordinary ones.
- Save attachments you need to OneDrive or SharePoint, then delete the messages or remove the attachments.
- Clear out old newsletters and notifications in bulk, by searching for the sender.
- Check Sent Items. Large attachments you sent are stored there too.
Keep it clear
- Share files as links instead of attachments.
- Ask about an online archive. Many Microsoft 365 plans include an archive mailbox where older mail can move automatically, keeping it searchable without filling your main mailbox.
- Ask whether your license fits. People who work mainly in email sometimes need a larger mailbox.
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Tell us what you run today and what is getting in the way. We will get back to you about how we can help.