If you’re switching to Mailcow from a classic mail host like 1&1, Strato, IONOS, AllInkl, Hetzner Mail etc., the migration is usually simpler than with MS365 or Google — no OAuth complications, no modern-auth hurdles, just IMAP to IMAP.
Two paths: you use the free IMAP migration tool in the mailbox backend yourself — with standard providers that’s usually enough. Or we handle the complete migration for a flat fee; the conditions are on the Mailhosting product page. The rest of this article describes the assisted variant.
What you give us
Per mailbox to migrate, we need:
- IMAP server of the old provider (e.g.
imap.1und1.de,imap.strato.de) - IMAP port (usually 993 with SSL)
- Username (often the full email address, sometimes a customer ID)
- Password
Plus: the mailboxes already created in Mailcow that we should migrate into.
Common server details of old providers
| Provider | IMAP server | Port | SMTP server | Port |
|---|---|---|---|---|
| 1&1 / IONOS | imap.ionos.de | 993 SSL | smtp.ionos.de | 587 STARTTLS |
| Strato | imap.strato.de | 993 SSL | smtp.strato.de | 587 STARTTLS |
| AllInkl | wXXXX.kasserver.com (X = customer no.) | 993 SSL | same pattern | 587 STARTTLS |
| mailbox.org | imap.mailbox.org | 993 SSL | smtp.mailbox.org | 587 STARTTLS |
| Posteo | posteo.de | 143 STARTTLS | posteo.de | 587 STARTTLS |
| GMX | imap.gmx.net | 993 SSL | mail.gmx.net | 587 STARTTLS |
| Web.de | imap.web.de | 993 SSL | smtp.web.de | 587 STARTTLS |
If your provider isn’t in the list: you’ll find the IMAP server address in the account configuration of your mail client.
We migrate with imapsync
Open a ticket: “Migration from <provider> to Mailcow, here are the mailboxes and credentials”.
Per mailbox, imapsync runs in the background:
- Initial sync: copy all mails from the old server to Mailcow
- Incremental sync: regular delta updates in case new mails arrive at the old provider
What we copy:
- All mails in all folders
- Original date and sender/recipient fields
- Read/unread status
- IMAP flags (flagged, answered, etc.)
What is not migrated:
- Server-side filters of the old provider
- Out-of-office notices
- Mail client rules (those were local anyway)
The cutover day — DNS switch
Day X-1, evening:
- We start the final delta sync.
- You change the DNS MX records at your domain registrar from
<alter-anbieter>to our mail servers. We give you the exact values. - DNS propagation: usually 30 minutes to 4 hours.
Day X:
- Mails now arrive at Mailcow.
- We run the last delta sync.
- End users switch their mail clients to Mailcow.
Day X+14:
- The mailbox at the old provider can be canceled or deleted.
Changing end users’ mail client settings
Per end user:
- Delete the old account in the mail client or change the server details to Mailcow.
- Server details for Mailcow:
| Field | Value |
|---|---|
| IMAP server | mail.xaweho.de, port 993, SSL |
| SMTP server | mail.xaweho.de, port 587, STARTTLS |
| Username | full email address |
| Password | mailbox / app password (see app passwords if 2FA is enabled) |
More in the server details reference.
From our experience: on cutover day, send a mail to all end users with instructions along the lines of “how to switch Outlook / Apple Mail / Thunderbird to the new server details”.
Calendar and contacts
Depends on the old provider:
- 1&1 / IONOS / Strato: usually no integrated calendar, so no migration needed.
- mailbox.org / Posteo: have SOGo/CalDAV calendars. Export as ICS, import into Mailcow SOGo.
- GMX / Web.de: export the calendar as ICS via the web interface.
Different per provider — open a ticket, we help depending on the source.
What can go wrong
Old servers have limits: 1&1 or Strato throttle IMAP connections per second. We set the pace accordingly — takes a bit longer then.
Very old mails are missing: some providers archive old mails server-side. Before migrating, check that all mails are still visible via IMAP.
Spam folder is missing: some providers (e.g. GMX) have a spam folder that isn’t accessible via IMAP. Mails in there are lost — go through it manually beforehand and keep what you want.
Subfolders with special characters: German umlauts in folder names (like “Geschäftspost”) can turn into “Gesch%C3%A4ftspost” during migration. Solution: rename the folders without umlauts before migrating, rename them back in Mailcow afterwards.
Webmail-specific features: Web.de and GMX have special features (saved searches, categories) that aren’t IMAP standard and can’t be migrated.
Costs at the old provider
From our experience:
- 1&1 / IONOS / Strato: the mail package is usually part of a web hosting plan. Cancellation is possible, but check whether the web hosting part is still needed.
- Web hosts with a bundled mail address: the address is often free within the plan, so no money to save by switching. Technically you can keep it at the web host as a spare, but MX points to Mailcow.
- Dedicated mail providers: separate mail products, clearly cancelable.
Note: With several mailboxes under one domain, Mailcow becomes cheaper per mailbox than most dedicated mail providers, which bill per address.
Frequently asked questions
Can we keep the old mail address at the old provider as a backup? Yes, technically. You don’t cancel right away and leave the mailbox at the old provider active. However: because of the DNS MX switch, mails only arrive at Mailcow. No new mails arrive at the old provider anymore.
How long should we run in parallel? We recommend 14–30 days. If something is missing or not working in Mailcow, you still have the old mailbox as a backup.
Can we receive new mails during the migration? Yes. As long as DNS MX points to the old provider, mails arrive there. We pull them over to Mailcow incrementally. Only the DNS switch changes the delivery path.
Can we also send from Mailcow during the migration? Yes, anytime. Mailcow SMTP works from the day the mailbox is created, regardless of the DNS status of the MX records.
What if the old provider only offers POP3, not IMAP?
Practically all modern mail hosts offer IMAP. If it really is POP3 only: your mail clients would have had to migrate the mails beforehand (POP3 downloads mails locally, then they’re gone from the server). In that case: export from the mail client as .mbox and import manually into SOGo.
Can we move our domain to xaweho too? We’re not a domain registrar — we host mail. Moving the domain to a new registrar (or keeping domain management with the old one) doesn’t matter for the migration. What matters: you must be able to change the DNS records at your current registrar.
What if the old provider bundles domain and mail? With AllInkl, 1&1, Strato that’s often the case. You can cancel the mail service there and keep the domain. You change the DNS MX records so they point to our mail servers — works without moving the domain.
What’s next
First login as domain admin in the Mailcow GUI
After ordering your mail server plan, you get access to the Mailcow GUI. Here's an overview of what you see as domain admin and where to find what.
Creating and editing mailboxes, setting quotas
How to create new mail addresses as domain admin, assign storage quotas, change passwords and delete mailboxes again.
Setting up aliases and a catchall
Route several mail addresses into one mailbox — info@, kontakt@, presse@ all in a single inbox. Plus a catchall for every typo address.
Creating app passwords for mail clients
With 2FA active, Outlook, Apple Mail and friends need an app password instead of your main password. How to create them, revoke them and avoid password chaos.