Do you need to migrate your email to a new hosting provider? Moving email accounts can be a challenge, but with the right approach migrating your email goes smoothly. In this guide we walk you through the entire process of migrating email.

You are switching to a new hosting provider and want to move your email along. Makes sense, because all your contacts, important messages and mail history are in that mailbox. In this article we explain step by step how to migrate your email without losing messages.

Preparation: what you need

• From your old provider: IMAP server, username and password
• From your new provider (Theory7): IMAP server (mail.theory7.net), your new email address and password
• DNS access: To change the MX records (often via your domain registrar)

Write down this information in a document. You will need it several times during the migration.

Step 1: Back up your old mailbox

Backup via a mail program

The simplest method is via a desktop program such as Thunderbird, Outlook or Apple Mail:

1. Add your old email account to the program (as IMAP)
2. Wait until all folders are fully synchronized
3. In Thunderbird: right-click on your account and choose "Export" to make a backup
4. In Outlook: go to File > Open and export > Import/export > Export to a file
5. Save the file safely, for example on an external drive or in the cloud

Backup via webmail

Some webmail systems offer an export function. Log in to your old provider and look for an option like "Export", "Download" or "Backup". This usually results in a .mbox or .eml file.

Tip: also take screenshots of your folder structure and any filter rules. You will need to set those up manually again later.

Step 2: Create a new mailbox at Theory7

1. Go to Email Manager or Email Accounts
2. Click Create Account
3. Enter the desired email address (use the same address as with your old provider)
4. Choose a strong password
5. Set the desired quota (storage space for the mailbox)
6. Click Create

Your new mailbox is now active. Test the connection by logging in to webmail via mail.theory7.net/webmail or webmail.yourdomain.com.

Step 3: Transfer email with IMAP synchronization

Method 1: Via a mail program (recommended for individuals)

This is the most accessible method and works for everyone:

1. Open Thunderbird, Outlook or Apple Mail
2. Add both accounts: your old mailbox and your new Theory7 mailbox
3. Wait until both accounts are fully synchronized
4. Select all folders in your old account
5. Drag the folders (or their content) to your new account
6. Wait until the copying is complete. This can take a while with large mailboxes.

Note: copy, don't move. This way your old mail stays intact as a backup until you are sure everything has come over correctly.

Method 2: ImapSync (for technical users)

Do you have many mailboxes or a large amount of data? Then ImapSync is a powerful tool that copies directly between two IMAP servers:

imapsync \
  --host1 mail.oldprovider.com --user1 info@yourdomain.com --password1 "oldpassword" \
  --host2 mail.theory7.net --user2 info@yourdomain.com --password2 "newpassword" \
  --ssl1 --ssl2

ImapSync preserves folder structure, read statuses and dates. It can also be resumed if the connection drops.

Method 3: Migration tools from your provider

Some hosting providers offer migration tools in the control panel. Ask your old provider whether they have an export function, and Theory7 whether an import function is available.

Step 4: Change DNS MX records

Changing MX records

1. Log in to your domain registrar or DNS manager
2. Go to DNS settings for your domain
3. Find the current MX records
4. Remove or change the old MX records
5. Add the new MX record:
   • Type: MX
   • Name: @ (or empty, depending on your provider)
   • Value: mail.theory7.net
   • Priority: 10
6. Save the changes

Propagation time

DNS changes take time to propagate worldwide. This is called DNS propagation and usually takes 1 to 24 hours, sometimes longer. During this period mail can still arrive at your old provider.

Tip: keep your old mailbox active for at least another week and check regularly for new messages.

Step 5: Check and finish

• Test receiving: send a test mail to your address from another account
• Test sending: send a mail and check whether it arrives
• Check folders: did all folders and subfolders come over correctly?
• Check special folders: Sent, Drafts, Trash, any custom folders
• Check dates: do messages still have the correct sent and received date?

Only once everything works and your old account stays empty for a week can you close it.

Step 6: Set up devices again

• Smartphone (iOS and Android): remove the old account and add the new one
• Desktop mail programs: update the server settings or reconfigure
• Web applications: update any SMTP settings for forms or notifications

Check our other guides for detailed instructions per device.

More about email and hosting

• Email hosting at Theory7 - professional email with your own domain
• Create an email address - step by step create your own email address
• Setting up SPF, DKIM and DMARC - prevent your mail from being seen as spam
• Setting up email on iPhone - guide for iOS

Migrating email: avoiding common mistakes

Mistake	Consequence	Solution
Closing old mailbox too soon	Losing mail due to DNS propagation	Keep old mailbox active for 2 weeks
Changing MX records too soon	Mail arrives at an empty mailbox	Fill the mailbox first, then change DNS
Not making a backup	In case of errors, mail is unrecoverably lost	Always back up before you start
Forgetting to update SPF/DKIM	Outgoing mail ends up in spam	Adjust SPF and DKIM after migration
Not updating devices	Mail does not work on phone/laptop	Reconfigure all devices

Migrating email: planning and timeline

Week 1: preparation

• Take stock of all email accounts that need to be migrated
• Write down passwords and server settings of the old provider
• Make a backup of all mailboxes
• Plan the migration moment (preferably on the weekend or outside business hours)

Week 2: performing the migration

• Create new mailboxes at Theory7
• Copy email over via IMAP synchronization or ImapSync
• Check whether all folders and messages came over correctly
• Change the MX records in your DNS

Week 3: checking and finishing

• Monitor whether new mail arrives correctly at Theory7
• Check the old mailbox daily for messages still arriving there
• Update all devices with the new server settings
• Adjust SPF, DKIM and DMARC records for the new mail server

Week 4: closing off

• Final check of all mailboxes
• Remove old email accounts only after everything works 100%
• Document the new settings for future use

Want to know more about email? Read about setting up SPF, DKIM and DMARC after your migration, or check out email hosting at Theory7.

Migrating email: large mailboxes and bulk migration

Mailboxes larger than 5 GB

Large mailboxes can cause problems when synchronizing via a mail program. The connection drops, the program becomes slow or the copy process stalls. In that case use ImapSync via the command line. ImapSync can resume where it left off and runs reliably with large datasets.

Multiple mailboxes at once

If you need to migrate ten or more mailboxes, manual processing is time-consuming. Create a script that runs ImapSync for each mailbox. Use a CSV file with the details of each mailbox and let the script process all accounts sequentially.

Minimizing downtime

With a business migration you want to keep the period without email as short as possible. Use this strategy:

1. Pre-migration: copy all existing mail while the old server is still active
2. Change DNS: change the MX records to the new server
3. Delta synchronization: run ImapSync again to catch messages that arrived in the meantime
4. Verification: check whether everything came over correctly

With this approach the effective downtime is minimal: only the few minutes it takes to change DNS and run the delta sync.

After the migration: updating email authentication

After migrating email, don't forget to update your email authentication records. The old SPF, DKIM and DMARC records point to your old mail server. Update these in your DNS so outgoing mail does not end up in the spam folder.

Need help with the migration?

• Transferring all your email to your new Theory7 hosting
• Correctly setting up DNS records
• Configuring mail programs on all your devices
• Solving any problems during the migration

Contact our support or ask about migration options when ordering your hosting package. We make sure your transition goes smoothly and you don't lose a single message.

Migrating email: summary and key points

Migrating email: preparatory steps

Taking inventory

Before you start the migration, map out the current situation:

• Number of email accounts - Make a list of all active email addresses and their storage usage
• Folder structure - Document the folder structure per account, especially if users use complex organization
• Forwarding rules and filters - Note all active forwarding rules and filter settings that need to be reconfigured
• Shared mailboxes - Identify mailboxes used by multiple employees
• Autoresponders - Turn off out-of-office messages before the migration to avoid confusion

Setting up a communication plan

Inform everyone involved well in advance about the migration. Send an email at least a week in advance with the migration time, expected downtime and instructions for updating email settings on phones and computers.

Migrating email: methods compared

Method	Suitable for	Speed	Complexity
IMAP synchronization	Small to medium migrations	Average	Low
Migration tool from provider	Migrations between large providers	Fast	Low
imapsync (command line)	Technical users, bulk	Fast	Average
PST/MBOX export/import	Small migrations, archiving	Slow	Low
Professional migration service	Large organizations	Fast	Provider handles it

Common problems when migrating email

• Missing emails after migration - Check the storage limits on the new server. If the mailbox quota is reached, not all messages are transferred. Increase the limit and run the migration again.
• Folder structure disappeared - Not all migration tools preserve the folder structure. Test with one account first before running a bulk migration.
• Emails do not arrive at the new account - After changing the MX records it takes a while before all messages are sent to the new server. Keep the old server active during DNS propagation.
• Loss of search functionality - After a large migration the search index needs to be rebuilt, which can take a while with large mailboxes.

By planning carefully and migrating step by step, you minimize the chance of problems and ensure a smooth transition to your new email environment. Don't forget to reconfigure your spam filters on the new server after migration.

Migrating email: checking and optimizing after migration

First check whether all email accounts work correctly by sending and receiving a test message for each account. Verify that messages are received correctly both via webmail and via desktop and mobile clients. Also check the sent folders, drafts and archive folders to confirm all data has been transferred correctly.

Then update all email settings on all your employees' devices. Create a concise guide with the new server details: incoming and outgoing server, port numbers and security settings. Distribute this guide in advance and plan a moment when employees update their settings, preferably with support available.

Finally, reconfigure your security records. Check whether your SPF record contains the new mail server, generate new DKIM keys if you switched providers, and update your DMARC policy. Test your email authentication with a tool like mail-tester.com by sending a test message and checking your score. A score of 9/10 or higher indicates your configuration is correct.

Monitor the first two weeks after migration extra closely for problems. Ask employees and customers to report if messages do not arrive or are delayed. Check the mail server logs daily for errors and the mail queue for stuck messages. After two weeks without problems, you can have the old mail server permanently decommissioned by your previous hosting provider.

Migrating email: summary and tips

Start preparations two weeks before the planned migration: take inventory of all accounts, document settings and set up a communication plan. Use IMAP synchronization or a professional migration tool to transfer all messages including folder structure. Keep both servers running in parallel for at least 48 hours to catch messages during DNS propagation. After the migration, update all email settings on all your employees' devices and reconfigure your SPF, DKIM and DMARC records for the new server. Monitor extra closely for problems in the first two weeks and be available for employees who need help updating their settings. With this structured approach your email migration goes smoothly and without loss of important communication.

Migrating email: an investment that pays off

Email migration checklist for businesses

For a flawless email migration follow this step-by-step checklist. Take inventory of all active email addresses, aliases and forwards that need to be transferred. Document the current DNS settings including MX, SPF, DKIM and DMARC records. Make a full backup of all mailboxes at the old provider. Set up the new environment with identical addresses and configurations. Set the DNS TTL to a low value at least 24 hours before the migration to enable fast propagation. Move the mailbox contents via IMAP synchronization or a migration tool. Change the MX records to the new server and monitor delivery for 48 hours. Verify that everyone involved can correctly receive and send before deactivating the old environment. Keep the old environment for at least another month as a safety net.

Check out our web hosting offering at Theory7 for reliable and fast hosting.