If you use POP3 in Outlook, messages are downloaded to your computer and removed from the server by default. To keep a copy on the server (so you can access them from other devices or webmail), you need to change a setting in Outlook. Alternatively, switching to IMAP eliminates this problem entirely.
Enable "Leave a copy of messages on the server"
File > Account Settings > select your account > Change > More Settings > Advanced tab > check "Leave a copy of messages on the server." Optionally set it to remove from server after a number of days to prevent the mailbox from filling up.
01. Enabling "Leave a Copy" in Outlook
This setting is only available for POP3 accounts (not IMAP, which always leaves messages on the server). The steps vary slightly by Outlook version but the path is the same:
- Open Outlook and go to File > Account Settings > Account Settings
- Select your email account and click "Change"
- Click "More Settings"
- Go to the Advanced tab
- Check "Leave a copy of messages on the server"
- Optionally check "Remove from server after X days" (we recommend 14-30 days)
- Click OK and then Next > Finish
02. Version-Specific Instructions
Outlook 2019/2021/Microsoft 365: File > Account Settings > Account Settings > select account > Change > More Settings > Advanced tab. The "Leave a copy" checkbox is under "Delivery."
Outlook 2016: Same path as above. If you don't see "More Settings," your account may be configured as IMAP (which doesn't need this setting).
Outlook for Mac: Go to Outlook > Preferences > Accounts > select your account. Under "Advanced," check "Leave a copy of each message on the server."
New Outlook (Windows): The new Outlook app uses Exchange ActiveSync or IMAP by default and doesn't support POP3. Messages stay on the server automatically.
03. Disk Space Considerations
Leaving messages on the server means they count toward your hosting account's disk space allocation. If you receive a lot of email with large attachments, this can consume significant space over time.
To manage this:
Set a removal period - Check "Remove from server after" and set it to 14 or 30 days. This gives other devices time to download the messages while preventing indefinite accumulation.
Also check "Remove from server when deleted from Deleted Items" - This syncs deletions so messages you trash in Outlook are also removed from the server.
For more on email and disk space, see Does Email Count Toward Disk Space? and Understanding Disk Space.
04. Switching to IMAP (Recommended)
If you want messages to stay on the server and sync across all devices automatically, switch from POP3 to IMAP. With IMAP, messages, folders, read/unread status, and deletions all sync between your devices and the server. No "leave on server" setting is needed because IMAP works this way by default.
To switch: remove your existing POP3 account from Outlook and add it back as IMAP using port 993 with SSL/TLS. Your messages on the server will reappear in the new IMAP account. Messages that were already downloaded to your computer via POP3 can be dragged into the new IMAP folders to upload them back to the server.
For the full comparison, see POP3 vs IMAP. For Outlook setup, see How to Set Up Email in Outlook.
Email Setup Help?
If you need help switching from POP3 to IMAP or configuring the leave-on-server setting, open a ticket.
Open a Support TicketQuick Recap: Leaving Messages on Server
- More Settings > Advanced tab in Outlook account settings
- Check "Leave a copy on server"
- Set a removal period (14-30 days) to prevent mailbox bloat
- IMAP is better for multi-device access and automatic sync
- Leaving copies uses server disk space - monitor your usage
Last updated March 2026 · Browse all Email articles
