Move your email from start to finish

1. Prepare both mailboxes

Keep the old service active and create the destination mailbox at your new provider. Confirm that you can sign in to both. The destination needs enough free storage for the messages you intend to copy; a full mailbox can interrupt a transfer.

Ask each provider for the IMAP server hostname, mailbox username, password or app password, encryption mode and port. Use the provider’s server hostname, especially if your domain’s DNS will change during the move. MailSync requires public IPv4 IMAP servers with password or app-password authentication. OAuth-only accounts and IPv6-only servers are not currently supported.

• SSL/TLS normally uses port 993. STARTTLS normally uses port 143. Follow your provider’s settings if they differ.
• If two-factor authentication is enabled, check whether the provider requires an app password and permits IMAP access.
• Back up important mail. Messages stored only in local folders on your computer need a separate transfer.
• Plan separately for contacts, calendars, forwarding, filters, signatures and other account settings.

Decide when you will switch email delivery, and leave time for checks before ending the old service. Do not cancel the source account as soon as the first sync finishes.

2. Create your account and plan credits

Create a MailSync account and verify your email address. Saving mailbox details is free. Buy credits before queuing a sync; credits are granted after payment is confirmed.

Each £5 credit covers one source and destination mailbox pair for six successful runs: an initial migration and five refreshes. The first queued run permanently assigns the credit to that pair. Failure, timeout or cancellation before execution restores the reserved run allowance, but the credit remains attached to that pair.

Plan to use refreshes around your switch. If a pair uses all six successful runs, another credit unlocks the next six.

3. Save and review connection details

Choose a new migration and give it a recognisable name. Enter the source details for the old mailbox and the destination details for the new one. Check the direction carefully: source is where the existing mail lives; destination is where you want the copy.

Set each server’s port and encryption mode independently. Leave certificate verification enabled so the connection checks the server’s identity. A TLS error is a reason to check the settings and certificate with your provider before changing verification.

Save the migration and review the mailbox pair before queuing it. Hostnames and usernames can be corrected before a credit is assigned. Once assigned, the mailbox identities cannot be changed to reuse that credit for another pair. Connection settings and passwords can be updated while the mailbox is idle.

For several mailboxes

Use New batch for up to 250 mailboxes with shared server settings. Each row uses the same username on both servers and separate source and destination passwords. CSV import accepts email and password columns and initially fills the same password for both sides; edit the destination password where needed. The CSV is parsed in your browser. Saving a batch does not queue jobs or spend credits.

4. Run the first sync

Queue the mailbox sync when you are ready. For a batch, select eligible mailboxes in the migrations list and choose Queue selected syncs. Each mailbox must have credentials and available allowance or an unused credit. Only one run per mailbox pair can be queued or running at a time.

The transfer runs in the background, so you can leave the page. Return to the migrations list or refresh the mailbox page to check whether it is queued, running, complete or failed. Run history records each attempt; MailSync does not currently provide detailed live message counters.

Duration varies with mailbox size, server limits and network speed. A single run has a one-hour process limit. If it fails or times out, check the safe failure message, correct the issue and queue a new attempt. Do not assume a failed run transferred nothing: check the destination too. A queued run can be cancelled before execution, but the interface cannot interrupt a running transfer.

5. Check the destination before switching

A completed run is your cue to inspect the new mailbox. Sign in through the new provider’s webmail or an email app configured directly for that provider.

• Compare expected folders and approximate message counts with the source.
• Open samples of older and recent messages, including messages with attachments.
• Check sent mail, nested folders and message flags important to your workflow.
• Confirm the destination still has enough storage and that the new account can send mail.

Providers can display folders differently, so investigate missing or unexpected folders before proceeding. Keep your backup and old account available while resolving discrepancies.

6. Switch email delivery with your provider

Once you are happy with the copied mail, change your domain’s MX records using the new provider’s instructions. MailSync does not edit DNS. If you do not manage your own domain or its DNS, ask your provider or administrator to handle this step.

Check the new provider’s instructions for SPF, DKIM and DMARC as well as MX records. Update email apps with the new incoming and outgoing settings, and test sending and receiving with an external account.

DNS caches can continue directing some mail to the old service during the transition. Keep both mailboxes accessible, monitor where new messages arrive and allow for the timing advised by your providers. A successful copy alone does not mean delivery has switched.

7. Refresh and verify after the switch

Queue another sync for the same mailbox pair to copy mail that arrived at the old service after your first run. You can use the remaining successful refreshes while delivery settles, checking both sides after each run.

Keep the source and destination connection details pointing to their respective providers. If a hostname follows your changed DNS to the new service, do not queue another sync until you have confirmed access to the original source with your provider. Choosing provider-specific hostnames before assigning a credit helps avoid this problem.

Check recent incoming messages, folder contents and external send/receive tests again. A refresh is a migration step, not continuous monitoring or a backup service. Decide when to run it based on what is still arriving at the old mailbox.

8. Finish and remove saved passwords

When delivery is stable, your final refresh is complete and your checks are satisfactory, remove saved mailbox passwords in MailSync while the mailbox is idle. Revoke migration app passwords with the provider if they are no longer needed. You will need to enter credentials again for any later sync.

Keep your backup and arrange closure of the old service only after confirming that you no longer need it. Complete any remaining contacts, calendars, forwarding and email-app changes separately.

MailSync is provided by TSI Hosting Ltd. For quick answers about compatibility, credits and password handling, visit the FAQ.