Back up a Outlook / Microsoft 365 mailbox
Download a complete archive of your Outlook / Microsoft 365 mailbox, no account needed, with the right IMAP settings already set up.
IMAP server and port already filled in for Outlook / Microsoft 365 — all that's left is to enter your credentials.
IMAP settings for Outlook / Microsoft 365
Outlook / Microsoft 365
- IMAP server
- outlook.office365.com
- Port
- 993
- Encryption
- SSL/TLS
- App password
- Required
Microsoft has disabled basic IMAP authentication on most personal and work accounts: an app password (or reconnecting via modern authentication) is required as soon as two-factor authentication is enabled.
App password for Outlook / Microsoft 365: Generate an app password from your Microsoft account security settings if two-factor authentication is on.
How it works
- Enter the credentials for your Outlook / Microsoft 365 mailbox — the server (outlook.office365.com, port 993) is already filled in.
- Start the backup — MailSync connects read-only and goes through all your Outlook / Microsoft 365 folders.
- A .zip archive is generated — one .eml file per message, same folder structure as your mailbox.
- Download your archive — available for 48 hours after the backup finishes.
What this tool doesn't do
- The operation only works over IMAP: a mailbox reachable only via POP3, or through a closed proprietary connector, can't be used.
- The archive doesn't contain your contacts, your calendar, or the filtering rules configured on the Outlook / Microsoft 365 server.
- Beyond 5GB, finishing the operation requires a one-off payment or the Premium plan.
Frequently asked questions
Do I need an app password for Outlook / Microsoft 365? +
Yes. Generate an app password from your Microsoft account security settings if two-factor authentication is on. Microsoft has disabled basic IMAP authentication on most personal and work accounts: an app password (or reconnecting via modern authentication) is required as soon as two-factor authentication is enabled.
Does the backup change my Outlook / Microsoft 365 mailbox? +
No. The connection to Outlook / Microsoft 365 is read-only: no message is deleted, moved, or even marked as read. Your mailbox stays exactly as you left it.
What format is my Outlook / Microsoft 365 mailbox backed up in? +
You get a .zip archive containing one .eml file per message, organized in the same folder structure as your Outlook / Microsoft 365 mailbox. The .eml format is an open standard, readable by Thunderbird, Outlook, Apple Mail and most email clients.
What Outlook / Microsoft 365 mailbox size is supported? +
The backup is free up to 5GB. Beyond that, the first 5GB are backed up for free, then you finish the operation for 4,99€ excl. VAT (5,99€ incl. VAT) or by switching to Premium, which removes this limit.
Are my Outlook / Microsoft 365 credentials stored? +
No. Your IMAP credentials are encrypted with libsodium for the duration of the operation, then erased as soon as it finishes. If you're signed in to your MailSync account and choose to save the mailbox, only that one is kept (encrypted); you can delete it at any time.