My mailbox is full: what now?

A full mailbox rejects new messages: the sender gets an error back that says mailbox full or quota exceeded, and you notice nothing yourself. The quickest way to free up space is to empty the trash and the spam folder first, and then delete or locally archive the largest messages with attachments from your inbox and your sent items. As soon as there is room again, new mail comes in as usual.

How to tell that your mailbox is full

• The sender gets the message back. The notice usually contains 552 5.2.2 Mailbox full, Quota exceeded or User is over quota. If the code starts with a 4, for example 452 4.2.2, the rejection is temporary and the sending server will try again later. If it starts with a 5, the message has been returned for good.
• You suddenly stop receiving anything, while sending still works.
• Your mail program can no longer save anything. Saving a draft or storing a sent message in the sent folder fails, because that also takes space on the server.

What takes up the space

• Attachments. A mailbox that is years old does not fill up with text, but with what is attached to it: invoices, photos, presentations.
• Sent items. Every attachment you sent yourself is stored there a second time. Almost nobody tidies that folder.
• Trash and spam. Both count until they are emptied.
• Drafts and copies over IMAP. All your devices keep their drafts and sent messages on the server.
• POP3 with a copy left on the server. Anyone using POP3 takes the mail off the server and should not have this problem, unless the setting that leaves a copy on the server is switched on. That is the most common cause of a full mailbox for someone who thought it could not happen.

Cleaning up in webmail

Start in webmail. There you work directly on the server, even when your mail program refuses to synchronise.

1. Sign in to webmail with your full email address and your password.
2. Empty the trash and the spam folder.
3. Open your inbox and sort by size, with the heaviest messages at the top.
4. Save the attachments you still need to your computer and delete the messages.
5. Do the same in the sent folder.
6. Empty the trash again. Deleted messages move there first and keep taking up space until then.

Cleaning up in Outlook

1. Sort the message list by size: click the current sort order above the list, usually the date, and choose Size.
2. In classic Outlook you will find Mailbox Cleanup under File, among the tools. Use it to find all messages above a certain size.
3. Delete what can go, in Sent Items as well, and then empty the Deleted Items folder.

Cleaning up in Apple Mail

1. In the View menu, choose Sort By and then Size.
2. Delete the heaviest messages, in the sent mailbox as well.
3. In the Mailbox menu, choose Erase Deleted Items and then Erase Junk Mail.

Archive instead of throwing away

Old mail that you have to keep does not need to stay on the server. An archive folder inside your regular mailbox does not help: it sits on the server just the same and counts towards the total. A local folder does help.

• Outlook: create an Outlook Data File (pst) and drag the old folders or years into it.
• Apple Mail: create a mailbox under On My Mac and move the messages there.

A local archive like that exists only on your computer and is not part of your hosting backup. So include it in the backup of your computer. Also agree on how long you keep mail: holding on to everything forever is not a strategy.

When a larger plan is the right step

The space for your mail is part of your hosting plan. If the mailbox is full again a few months after cleaning up and archiving, a larger plan is more honest than cleaning up every month. The plans are listed on hosting pricing; what comes with mail on your own domain is described on email hosting. If it is not only your mail but your whole hosting account that is filling up, read what happens when your hosting is full.

Common mistakes

• Deleting messages and forgetting the trash. Not a single byte is freed.
• POP3 on the phone and IMAP on the computer. The phone removes mail from the server or leaves everything there, depending on a single checkbox. Set up every device the same way: see setting up email on your iPhone or Android.

Frequently asked questions

Will the rejected mail still arrive once I free up space?

Only if the rejection was temporary and the sender's server is still retrying. A message that was returned for good has to be sent again by the sender.

Why is my mailbox full when my inbox is almost empty?

Because every folder counts. Look at the sent items, the trash, the spam folder, the drafts and the archive folders you once created yourself.

How do I stop it from happening again?

If your webmail or your mail program shows how much space is in use, check it now and then and clean up at around eighty percent. It is better to step in yourself in time than to hear from a customer that their message bounced.

Still stuck?

If you can no longer sign in to webmail, or the mailbox stays full after cleaning up, let us know via contact, with the email address and the error message the sender received.