Moving in from another host

Any host that speaks IMAP can be moved from, and the procedure is the same for all of them. The order matters: the archive is copied before the MX record changes, and copied once more afterwards, so that nothing delivered during propagation is left behind.

Your old mail comes across with the importer. On each mailbox's page, Import mail from another provider connects to the old host, copies the folders you choose with their messages, dates and read state, and runs in the background. There is nothing to install, and nothing is deleted at the old host. How the importer works.

Before you begin

A list of every address at the old host, and whether each is a mailbox or an alias. An alias stays an alias here on every plan (into one of your mailboxes, and replying as itself on that mailbox's domain).
Each mailbox's password at the old host, or an app password where the host asks for one (Gmail, Google Workspace, Yahoo, iCloud, Zoho, Fastmail). The importer shows how to make one. In Google Workspace an admin can switch app passwords off; ask them first.
Access to the domain's DNS: the registrar or DNS provider, not the old mail host's panel.
For a host the importer does not list, its IMAP server name (for example Rackspace secure.emailsrvr.com, port 993). The common providers are filled in for you.

The cutover, in order

Add the domain and publish only the ownership record. The TXT record at _foundermail proves the domain is yours and changes nothing about where mail goes. Wait for the domain page to show ownership as proved.
Create the mailboxes with the same local parts as at the old host.
Enable sending and publish its records. From the domain's Sending tab: three DKIM CNAME records and the bounce subdomain's MX and TXT. Add include:foundermail.mx to your existing SPF record alongside the old host's include, so both can send during the overlap. None of this affects receiving.
Import the archive. On each mailbox's page choose Import mail from another provider, pick the old provider and sign in. Up to three mailboxes import at the same time, and you can carry on working while they run.
Change the MX record to 10 smtp.foundermail.mx and remove the old host's MX records. The domain page re-checks every ten seconds and shows receiving as verified once the change is visible.
Point mail clients at FounderMail, using the settings on each mailbox page (the client settings).
Import once more, a day later. Any message the old host received while DNS propagated is picked up. Messages already here are skipped, so nothing is doubled.
Request outbound access if you write first to people who have not written to you (invoices, onboarding). See Sending and outbound access.
Cancel the old host after a week of normal mail, then remove its SPF include.

The importer

The short version is below; the steps for each provider, what is copied and what to do when something goes wrong are in Importing mail from another provider.

Open the mailbox the mail should go into and choose Import mail from another provider.
Pick the old provider: Gmail, Google Workspace, Outlook.com / Microsoft 365, Yahoo, iCloud, Zoho or Fastmail are filled in. For any other host choose Another IMAP server and type its server name.
For Outlook.com and Microsoft 365, press Sign in with Microsoft and sign in as usual; there is no password to copy. For the others, enter the old address and its app password (or password, for hosts that do not use app passwords), and press Test connection.
Tick the folders to bring and how far back to go (everything, or the last few months or years), and start. Progress shows on the page and you get an email when it is done.

Inbox, Sent, Archive and your own folders are ticked by default and land in the matching folders here; Drafts, Junk and Trash are offered but left unticked. In Gmail, mail you archived comes from All Mail into Archive, Starred and Important are views and are skipped, and a message with several labels is brought once. Imported sent mail shows in Sent but does not count against your sending limits. Messages the old provider had marked as deleted are left behind. Original dates, read and starred state and attachments are kept. Imported mail appears in the dashboard like any other, grouped into conversations.

It takes roughly five to ten minutes per thousand messages. Messages already here are skipped, so running it again never makes duplicates. The old password is kept encrypted while the import runs and deleted when it ends, and nothing is changed at the old provider.

Imported mail counts toward your account's pooled storage: 1 GB on Free, 15 GB on Plus, 50 GB on Pro, 250 GB on Scale. If the archive is bigger, import a shorter range; an import that runs out of room stops and says so. Start it again after an upgrade: what is already here is skipped.

Outlook.com, Hotmail and Microsoft 365. You sign in with Microsoft and approve read access to your mail; FounderMail never sees your password, keeps the sign-in only while the import runs, and changes nothing in the old mailbox. Calendar, Contacts and Tasks are not mail and are skipped. On a work or school account your organisation may require its IT admin to approve FounderMail first, or may have IMAP switched off for the mailbox; the importer says which, and gives your admin the link to approve it.

Other ways to copy

Two alternatives remain for the cases the importer does not cover: a host it cannot sign in to, or a tool you want to run yourself.

With a mail client

Suited to one to three mailboxes.

In Thunderbird or Apple Mail, add the old mailbox as an IMAP account, then add the new one (imap.foundermail.mx, port 993, SSL/TLS, the full address as username).
Wait for the old account to finish syncing headers.
Select all messages in a folder at the old account and drag them to the matching folder at the new one. Repeat per folder. Sent, Drafts, Junk and Trash are the same folders on both sides because FounderMail marks them with their IMAP role.
Leave the client open until the upload completes; a large archive can take hours.

With imapsync, for technical users

For people who prefer a command-line tool they control. Run once per mailbox:

imapsync \
  --host1 secure.emailsrvr.com --ssl1 --user1 hello@yourdomain.com --password1 'old-password' \
  --host2 imap.foundermail.mx   --ssl2 --user2 hello@yourdomain.com --password2 'new-password' \
  --automap

--automap maps Sent, Drafts, Junk and Trash by their IMAP role even when the old host names them differently.
Add --dry first to see what would be copied without copying it.
Add --folder "Some label" to copy only one folder, for example one Gmail label.
Re-running the same command later copies only what is new.

Checks afterwards

The domain page shows ownership proved, receiving verified, and sending verified.
A message from an external account arrives in the Inbox within a minute.
A reply from the dashboard arrives at the external account and passes SPF and DKIM (most providers show this under "show original" or "view headers").
dig +short MX yourdomain.com returns only 10 smtp.foundermail.mx.

Host-specific guides

Leaving Rackspace, with a price comparison.
Leaving Gmail and a forwarder before "Send mail as" ends in January 2027.