How to migrate email to a new host

Moving email has one rule: mail must always have somewhere to land. Create the new mailboxes first, copy the old mail across, switch the MX records, then copy again to catch anything that arrived during the change.

Create the mailboxes at the new provider, copy existing mail across with IMAP, switch the MX records, copy again to catch stragglers, then move each person’s devices. Mail keeps arriving throughout, so done in this order, nothing is lost.

What moves and what does not

Item	Moves with IMAP copy	Do it separately
Emails in every folder	Yes
Sent items and drafts	Yes
Contacts	No	Export as vCard or CSV, import at the new provider
Calendars	No	Export as `.ics`, import
Filters and rules	No	Recreate by hand
Aliases and forwarders	No	Recreate at the new provider
Signatures	No	Recreate in each app
Auto-replies	No	Recreate

Mailboxes downloaded with POP3 (rather than IMAP) usually have nothing left on the server to copy: the mail lives in the person’s mail app. Move it by adding the new account to that app over IMAP and dragging folders across.

Before you start

List every mailbox, alias and forwarder on the old host.
Get the IMAP server name and a password for each old mailbox.
Create the same mailboxes, with passwords, at the new provider.
Lower the TTL on your MX records to 300 seconds a day ahead.

1. Copy existing mail over IMAP

Many providers have a built-in migration tool that logs into the old server and copies everything. If yours does not, imapsync is the standard command-line tool:

imapsync \
  --host1 mail.oldhost.example --user1 you@example.com --password1 'old-pass' \
  --host2 mail.newhost.example --user2 you@example.com --password2 'new-pass'

It copies every folder and skips messages that already exist, so you can run it again safely.

2. Switch the MX records

Replace the old MX records with the new provider’s, and add their SPF include and DKIM record. See SPF, DKIM and DMARC. New mail starts arriving at the new provider as the change spreads.

MX records for common providers

Provider	MX record
Google Workspace	`1 smtp.google.com.`
Microsoft 365	`0 example-com.mail.protection.outlook.com.` (your exact value is in the admin centre)
cPanel hosting	Usually `0 example.com.` or `mail.example.com.`, set by the host

Remove every old MX record, not just the first one. A leftover old record with a lower priority number keeps receiving some of your mail.

3. Copy again

Run the same imapsync command a day later, and again after three days, to pick up messages delivered to the old server by senders whose DNS had not caught up.

Check mail is arriving at the new provider

dig example.com MX +short

Once it shows only the new provider, send test messages from an outside address, such as a personal Gmail, to each mailbox. Then check the old server’s mail log or webmail for any new arrivals; when none arrive for a day, the switch is complete.

4. Move people’s devices

Update every phone and mail app with the new server settings, or remove and re-add the account. This is often the slowest part; send everyone the new settings in advance.

Typical settings for mail apps

Setting	Usual value
Incoming (IMAP)	Port 993, SSL/TLS
Outgoing (SMTP)	Port 465 (SSL/TLS) or 587 (STARTTLS)
Username	The full email address

Most apps detect these automatically from the address alone, if the provider publishes autodiscover or autoconfig records. Check the provider’s setup page and add any autodiscover CNAME or SRV records it lists.

Do not cancel the old email service until the final copy has run and every device has moved. Messages left only on the old server are lost when the account closes.