Provider reference

Provider settings and the gotchas.

Host, port, where to get an app password and what the provider does differently from what you expect. Everything here is what breaks a transfer in the first minute.

Providers

Gmail / Google Workspace

imap.gmail.com : 993

The most common source, and the most common place a transfer trips over. Gmail has no folders — it has labels, so a single message shows up in several “folders” at once, and a naive transfer happily produces duplicates.

Serverimap.gmail.com

Port993 · SSL/TLS

Usernamefull address

Passwordapp password

Step by step

Turn on two-step verification in your Google account — app passwords are not available without it.
Open the App passwords page, create a password named MoveMailbox and copy the 16 characters.
In Gmail: Settings → Forwarding and POP/IMAP → “Enable IMAP” → Save.
Paste the app password into the password field with no spaces. Your normal account password will not work.
On Google Workspace, check that the admin has not disabled IMAP for the organisation.

Gotchas

The All Mail label — [Gmail]/All Mail holds a copy of every message. Leave it in and the volume doubles while duplicates land in the destination.
Volume cap — Gmail serves roughly 2,500 MB per mailbox per day over IMAP. A large archive takes several days; that is normal, not a fault.
Trash and Spam are usually not worth moving: untick [Gmail]/Trash and [Gmail]/Spam.
Temporary block — push too hard and Google suspends IMAP for a few hours. We keep a single stream and pause between folders.

The imapsync equivalent — what MoveMailbox puts together for you

imapsync \
  --host1 imap.gmail.com --port1 993 --ssl1 \
  --user1 anna@old.com --passfile1 /run/secrets/p1 \
  --host2 imap.new.com --port2 993 --ssl2 \
  --user2 anna@new.com --passfile2 /run/secrets/p2 \
  --exclude "^\[Gmail\]/All Mail$" --exclude "^\[Gmail\]/Spam$" \
  --automap --dry

Guide

Guides

Single topics taken apart: what to choose, why, and how to read the server’s answer.

Migrating mail while the domain has not moved yetHow to connect while DNS still points at the old server: use the hosting provider’s own hostname, when an IP actually works, and why certificate checks stay on.Go to the transfer IMAP ports and encryptionWhich IMAP port to pick, how SSL/TLS differs from STARTTLS, why plain 143 is not an option, and what the usual connection errors actually mean.Go to the transfer Changing hosting: how to migrate the mailThe order of a mail migration during a hosting change: where cPanel, Plesk and DirectAdmin show IMAP settings, when to switch MX, and what IMAP does not carry over.Go to the transfer Corporate email migrationHow to move a company’s mail to another server: mailbox inventory, a pilot run, access in Microsoft 365 and Google Workspace, migration waves and reconciliation.Go to the transfer

FAQ

Before your first transfer

What happens to my password?

The connection runs over HTTPS. Before a job is queued, the credentials are encrypted for the worker: the plain password is never stored, only an encrypted package is kept for a while. It is decrypted in the worker’s memory and passed to the imapsync process through the environment. The password never shows up in the logs, and you enter it again for a rerun. If that model is not enough, there is the self-hosted version, where the password goes to your own mail servers and no MoveMailbox infrastructure is involved.

What do the free 5 GB mean?

One whole mailbox measured at 5 GB or less moves for free. We will not copy the first 5 GB of a large mailbox and then stop out of the blue.

Can I close the browser?

In the hosted version the job runs on our worker and keeps going after you close the tab. The local Windows client has to stay open.

What if the transfer breaks off?

Start it again. imapsync checks what is already on the destination and copies only what is missing — a rerun is cheap and creates no duplicates.

Why does Windows have no cloud limit?

The work and the traffic are handled by the user’s own machine, so the commercial MoveMailbox Cloud limit does not apply. Provider-side limits still do.

Does the old mail get deleted?

No. The default scenario is a one-way copy. Only delete the old mailbox after checking things by hand and letting a grace period pass.

Which servers are supported?

Any compatible IMAP server. Gmail, Microsoft and some corporate systems may require an app password, IMAP to be switched on, or OAuth.

Are dates, flags and attachments preserved?

Yes. The original RFC-822 object is moved whole: headers, date, attachments, read/answered flags, nested folder structure. Server-side filters, auto-replies and contacts are not moved — they are not part of IMAP.

Find out how big your mailbox is. It costs nothing.

Connect two servers, look at the size and decide. Or take the client and keep everything on your side.

Start the transfer Download for Windows

Code on GitHub · built on imapsync · no sign-up