Webmail request
en
Webmail request
nl en fr de
Setup & how-to

Email migration: copying your IMAP mailbox (Thunderbird/ImapSync)

You copy your IMAP mailbox by putting your old and new accounts together in one mail program and simply dragging your folders across. For a large mailbox it's faster with the free tool ImapSync, which copies directly from server to server. Your old messages are preserved in the process: copying moves nothing, it makes a second copy on your new Mailflux mailbox. We'll walk you through both methods step by step, and only once everything checks out do you need to say goodbye to the old mailbox.

By the Mailflux team Published on

What you need

  • Access to your old mailbox: the full address and password. With some services you need a separate app password if you use two-factor authentication.
  • Your new Mailflux mailbox with its address and password.
  • A mail program such as Thunderbird, or the tool ImapSync for larger transfers.
  • The server settings: IMAP on port 993 with SSL, SMTP on port 465 with SSL. You'll find the exact Mailflux server name in your Mailflux account or on the IMAP and server settings page.

Want to see the whole plan first? Then take a look at the checklist for your email migration.

Email on your own domain

Copying your IMAP mailbox: step by step

With Thunderbird (the simplest way):

  1. Add your old account in Thunderbird via IMAP. That way the original messages stay untouched on the old server.
  2. Then add your new Mailflux account, also via IMAP. If needed, see setting up email in Thunderbird for the exact fields.
  3. Wait until both folder lists are fully loaded. With a large mailbox that can take a while.
  1. On your Mailflux account, create the same folders if necessary (for example Archive, Projects).
  2. Open your old Inbox, select all messages with Ctrl+A, and drag them to the corresponding folder on your Mailflux account. Right-click → Copy to works too.
  3. Repeat this per folder: Sent, Archive, Drafts, and so on.
  4. Check that the number of messages per folder is the same on both sides.

With ImapSync (for large or many mailboxes):

  1. Install ImapSync or use the web version.
  2. For host1 enter your old server and for host2 the Mailflux server name, each with your address and password.
  3. Start the synchronisation. ImapSync copies all folders and preserves the read status. Run it again later and only the new messages are added.

Your messages are preserved

Copying is not the same as moving. As long as you only copy, each message will sit in two places afterwards: on your old mailbox and on Mailflux. So only delete the old mailbox once you've checked that everything has come across. To play it safe, read how to move your email without losing anything from start to finish.

Not working?

  • Password refused. Use the mailbox's own password. With two-factor authentication on the old service you need an app password.
  • No connection. Check that you use port 993 with SSL for incoming and port 465 with SSL for outgoing, and that the server name is correct.
  • Folders don't load fully. Right-click the account → Subscribe and tick all the folders.
  • Copying stops halfway. Copy per folder in smaller selections, or use ImapSync, which resumes by itself.

Done, and need help?

If the counts match on both sides, your mailbox is safely copied. Keep your old mailbox for a while until you're sure you're not missing anything. Want to plan the full move neatly? Then follow step by step how to move your email without losing anything. Rather not tinker yourself? Feel free to let us handle your migration, and we'll help you get going personally.

Want to do it yourself?

Follow our step-by-step guide, or let us help you get set up personally.

Read the guide

FAQ

Frequently asked questions

Will I lose messages if the copying goes wrong?

No. You copy from your old mailbox, so the originals simply stay there as long as you don't delete anything. If the copying stalls, you start it again. Only once you've checked that all folders and counts on Mailflux match can you safely clear out the old mailbox.

Are my folders and read status preserved with ImapSync?

Yes. ImapSync brings your entire folder structure along and preserves whether a message is read or unread. Run the tool again later and it only copies what's newly arrived. That way you can move things across in advance and update once more just before the final switch.

Read more