Will outbound port 25 be open?

Yes on AnubizHost - port 25 is open by default. New IPs may have very limited initial reputation; warm gradually and consider using a transactional sending service for high-volume outbound until reputation builds.

What if I need to keep the old IP for a few days?

Run dual-MX with both old and new IP both reachable. Set the new IP as primary MX (lower preference number), keep old as secondary. After 7 days of clean traffic on new, remove old MX entry.

How do I handle Mailcow updates after migration?

Use ./update.sh in the mailcow-dockerized directory. The update process is identical to before migration.

What about catchall and forwarding rules?

All forwarding, catchall, alias, and filter rules are stored in the database and migrated with the data tarball. Nothing to reconfigure.

Migration Guides

Migrating Mailcow to AnubizHost

Mailcow Dockerized bundles Postfix, Dovecot, SOGo, Rspamd, and ClamAV into a tested Docker Compose stack. Migration is a clean tarball-and-rsync because the entire state lives in mailcow-dockerized/data. This guide walks through moving a Mailcow install to AnubizHost offshore VPS with deliverability preserved.

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Prep the Source Mailcow

From the mailcow-dockerized directory on source, run ./helper-scripts/backup_and_restore.sh backup all. This creates a tarball with all data. Alternatively, manually stop the stack and tar the entire mailcow-dockerized directory.

Note the FQDN configured in mailcow.conf. The FQDN stays the same; only the IP changes.

Provision AnubizHost Target

Order offshore VPS with at least 4GB RAM (Mailcow runs ClamAV which is memory-hungry). Romania and Iceland are good fits - both have clean mail IP reputation pools. Open ports 25, 465, 587, 993, 995 in firewall.

Install Docker and Docker Compose: curl -fsSL https://get.docker.com | sh. Clone mailcow-dockerized at the same version as source.

Transfer Data and Bring Up Stack

Stop the source stack: docker compose down. Rsync the entire mailcow-dockerized directory to the target:

rsync -avHAX /opt/mailcow-dockerized/ \
  root@NEW_IP:/opt/mailcow-dockerized/

On target: review mailcow.conf, update MAILCOW_HOSTNAME if changed, run docker compose pull and docker compose up -d.

DNS, MX, PTR, and Reputation

Update MX records to point at the new hostname. Update SPF (v=spf1 ip4:NEW_IP -all). DKIM keys are inside the data volume and don't change. Open a ticket with AnubizHost to set PTR (reverse DNS) for the new IP - critical for mail deliverability.

Warm the new IP gradually if it's brand new - send a few hundred messages day 1, ramp up over 7 days. Monitor postmaster tools at Google and Microsoft.

Operational Notes

Mailcow backups: cron ./helper-scripts/backup_and_restore.sh backup all-without-mail nightly, archive to AnubizHost offshore storage. Mail itself backs up via vmail volume - rsync to storage VPS. Related reading: offshore email hosting, OVH mail migration, anonymous hosting.

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