Migrating an OVH Mail Server to AnubizHost
Mail server migrations are unforgiving: lose a message and your users notice immediately. This guide covers the safe path from an OVH-hosted Postfix/Dovecot or Mailcow stack to an AnubizHost offshore VPS, including IMAP sync, MX cutover, and the DNS authentication records (SPF, DKIM, DMARC) that keep your mail out of spam folders during the transition.
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Audit the OVH Mail Setup First
List every domain, alias, and mailbox on the OVH side. If you run cPanel, export accounts via /scripts/pkgacct. If you run Mailcow, dump the database and the Vmail directory. For plain Postfix/Dovecot, list mailboxes from /etc/postfix/virtual or your LDAP backend and note the storage location (/var/vmail by convention).
Record current DNS values for MX, SPF (v=spf1 ...), DKIM (default._domainkey or your selector), and DMARC (_dmarc). You will keep most of these unchanged and only swap the host portion.
Stand Up the AnubizHost Mail VPS
An offshore VPS in Romania or Iceland is a good fit for mail because both jurisdictions are off most spam blocklists and have clean IP reputation pools. Order a VPS with at least 4GB RAM if you expect 50+ mailboxes (Dovecot index memory adds up). Install your preferred mail stack: apt install postfix dovecot-imapd dovecot-pop3d opendkim rspamd for a hand-rolled setup, or pull Mailcow Dockerized for a managed install.
Open ports 25, 465, 587, 993, 995 in your firewall but keep 25 inbound rate-limited until reputation is warm. Add a PTR record (reverse DNS) on the new IP - open a ticket through the AnubizHost panel to set it before mail flow begins.
Sync Mailboxes with imapsync
The gold standard for mail migration is imapsync. Install it on a third box (or the new server) and run per-user:
imapsync \
--host1 mail.ovh-old.example --user1 alice@example.com --password1 OLD \
--host2 mail.new.example --user2 alice@example.com --password2 NEW \
--ssl1 --ssl2 --automapFor batch migration, loop over a CSV of credentials. Run an initial full sync 24 hours before cutover, then a delta sync immediately before flipping MX records. imapsync is idempotent so you can re-run safely.
Cut Over MX, SPF, DKIM, DMARC
Lower MX TTL to 300 seconds the day before. At cutover, change MX to point at the new hostname (e.g. mail.new.example). Update SPF to include the new IP: v=spf1 ip4:NEW_IP -all. Generate a fresh DKIM key on the new server and publish the public key as a TXT record at default._domainkey.example.com. Leave DMARC at p=none for the first 48 hours to monitor without bouncing legitimate mail.
Test deliverability with mail-tester.com from the new IP. Score should be 9+/10 before you announce the cutover internally.
Warm the New IP Reputation
Fresh IPs land in spam folders if you blast 10,000 messages on day one. Ramp gradually: 500 messages day 1, 1500 day 2, 5000 day 3, then full volume by day 7. Monitor postmaster tools at Google (postmaster.google.com), Microsoft (sndsi.windows.com), and Yahoo. Related reading: email hosting overview, anonymous hosting, bulletproof hosting for sensitive comms.
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