Modern email systems that use IMAP (like iCloud and Google/Gmail) keep your messages on the server indefinitely. This makes your inbox, sent messages and others available every device you use – Mac, iPhone, iPad or web mail. You may create other mailbox folders that sync with your devices by saving them in the section named after your mail service (iCloud, Gmail or your company).
Every system has its limits, and if you exceed your mail quota you may no longer receive new messages. You can check your mailbox usage and quotas by selecting your inbox and typing Command-I (Get Info). If you're within 90% of the total available space you should take action soon. If you're near or over 100%, do it immediately – messages may be returned to the sender.
The standard Archive button at the top of the Mail window may not reclaim space on the email server. Your Inbox, Sent and Trash count against your quota. So do any folders under your iCloud, Gmail or the company section. You can reduce your storage by deleting old messages you no longer need. Then, click the Trash mailbox, select them again and delete from trash. That’s the only way to remove them for good. When you’re done, check your email quota and see if you’re below 70%.
Need to keep old messages? While the email server has a limit, your Mac can hold tens of thousands of messages. If you move them to a mailbox folder in the section called On My Mac, you’ll free up space on the server and still be able to use them normally… as long as they’re in the computer’s local mailboxes.
Archiving messages in Mail
- Open the Mail app.
- Make sure you can see the mailbox list on the left side. Click the View menu and Show Mailbox List if it’s missing.
- Click the + button under the mailboxes. Call it Archived Inbox and save it in the On My Mac section.
- Click the Inbox and scroll down, then select messages – perhaps selecting messages older than 6 months.
- Drag the messages to the Archived Inbox mailbox in the sidebar.
- Wait for the messages to transfer. It may take a while – you can see progress at the lower-left corner of the Mail window or click the Window menu and choose Activity.
- Click the Archived Inbox and verify that the messages copied.
- Click the Inbox again and delete the messages.
- You may repeat these steps for your sent messages. Create an Archived Sent mailbox in the On My Mac section and drag items from the Sent folder. Wait for them to copy, then delete them from Sent.
- Click the Trash icon in Mail and select the messages one more time. Delete them again to regain space on the server.
Leave the Mail app open, with the computer plugged in and awake while messages are transferred.
If you have mailboxes in the iCloud, Gmail or company section you can drag the mailbox folder itself to the On My Mac section. Wait until the transfer completes before you do others. You want to avoid overwhelming Mail or have stop in the middle. Then confirm that everything made it across and delete the original messages or mailbox folders.
Read more about organizing messages in mailboxes.
Learn more about email & iCloud.
