How to send emails when it tells me my mailbox is full but it is empty

Thanks for bringing this up. I understand your concern, and I will guide you through it.

This usually happens when the account is out of sync on the Mac. Since mail is still working on your iPad and phone, the account is fine on the server side.

Here are some basic steps you can try to fix it:

1. Check the mailbox size in Webmail

Sign in to your email using a web browser (Outlook.com, Gmail, iCloud, or your provider’s site).

• Confirm the mailbox is not actually full. If it is, clear some items from Inbox, Sent, or Deleted Items.

1. Remove and re-add the account on the Mac
   • Go to System Settings > Internet Accounts (for Apple Mail) or Outlook > Tools > Accounts (if using Outlook for Mac).
   • Remove the email account, restart your Mac, and then add it back.
2. Empty Deleted Items and Junk folders
   • Sometimes, hidden or sync-stuck items in Trash or Junk can trigger the full warning. Empty them fully in Webmail and on your Mac.
3. Rebuild mailbox on Mac (if using Apple Mail)
   • Open the Mail app, select the mailbox in the sidebar.
   • Click Mailbox > Rebuild from the top menu.
   Check sync type If the account is POP, switch to IMAP instead so all devices stay in sync with the server.

These steps usually resolve the issue. For reference, you can also check these articles:

Manage my mailbox size in Outlook

Microsoft storage

Storage limits in Outlook.com

Let me know how it goes. I will stay with you until we get this fully resolved.

Note: There are links to a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.

Please use the Add a comment section below this message to reply, instead of using the Answer field, so that I’ll be notified of your response.