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Migrating from BT business email lite to BT Office 365 Business Premium


 I have two domains owned and managed through BT for which the users currently have BT business email Lite. We use an onsite email server to provide MAPI to sync across multiple devices.

We want to move all the users to BT Office 365 business premium and get rid of the onsite email server. There is no need to migrate all of the email (as we already have it) but we don’t want any downtime or loss of email.

When I attempt to register the first domain with the Office 365 Admin site, it tells me that I can’t do this as it is already registered with another Outlook 365 tenant. My plan to just repoint the MX record to the new service won’t work.

The advice on line seems to be to remove the accounts from the POP3 service, disassociate the domain and recreate in the new tenant. There are three issues with this. Firstly, this could result in lost email during transition. Secondly, I don’t have permission to do this on the POP3 tenant. Thirdly one of the email accounts I want to move is also the primary BT account and administration(deactivation) of this account is greyed out.

How do I get the domain setup in the new Outlook 365 tenant so I can move the email accounts and repoint the MX record? I could temporarily reroute the MX record to the on-site server to avoid any loss of email.


BT Employee
BT Employee

Hi Hlees


My apologies you have not recieved a reply to your query until now.


In regards to this, what you have been advised is correct - you need to deactivate all existing email lite accounts on your domain. I understand this is likely frustrating given the circumstances, but to my knowledge that is the only way to move across. We would always recommend backing up all your emails before doing this to prevent loss.


In terms of deactivating the greyed out email you would need to create a new email address, promote this to admin, and that would then enable you to deactivate the previous admin email, enabling you to register on the new tenant.


I would recommend giving our tech team a call on 0800 800 154 to discuss that further if you have not done so already, they should be able to assist you with this and help you get the mailboxes deactivated.


All the best with this one!




Apologies for bringing back an old thread. 


I'm in the same position as the OP. How can a new email address be created without it being assigned a Business Lite account which in turn would need to be deactivated? Is there a way to use a gmail account account for this?

Do all @btconnect accounts become Business Lite accounts?




I'm also struggling with this a bit further down the line.


I can't even work out how remove the email accounts after backing up the inbox (BTW you can't backup sent items or any other folder including any archive folders so we resorted to moving everything back into the inbox as that is literally the only way we could access the emails outside of webmail (which of course doesn't have any exporting features either)) 


No clue how to disassociate the domain either The FAQs are either old and/or irrlelevant. The poor BT support guy I called was way out of his depth when I asked so we just went round and round with me saying we need to disable something in the control panel and him saying the as the DNS entries weren't with BT, it was our responsibility. I couldn't even explain the problem to him so he understood the issue. 


Hi Ryan. Similar situation. Exactly how do you delete the mailboxes and disassociate the domain from BT Email Lite? There was nothing in any of the control panels I could find. 


Yikes Jesse!!!!

@jessewalter375 wrote:

Open Outlook.
If the Microsoft Outlook Startup wizard appears:
Click Next on the first page.
On theE-mail Accounts page, click Next to set up an email account.
If the Startup wizard doesn't appear:
Click the File tab on the Outlook toolbar.
Above the Account Settings button, click Add Account.
Click Manually configure server settings or additional server types, and then click Next.
Select Internet E-mail and click Next.
In the Account drop down choose POP3.
In the Incoming mail server field, type ''.
In the Outgoing mail server field, type ''.
Type your email address in the Username field.
Enter your email password in the Password field.
Click on More Settings.
Select the Outgoing Server tab.
Tick My outgoing server requires authentication.
Select the radio button next to Use the same settings as my incoming server and click OK.


Hope this helps.


You also need to go into the Mail settings and make sure 'Remove from server after 14 days' is unticked. 

And in any case, all you will get with that is the inbox, not sent items, any additional folders, the contact list or calenders. Even the 'safely stored' archive folders are inaccesable to any backup system I could find. If you've used the Lite service as basically an online one, 90% of the emails have become impossible to back up.

Grand Guru

BT Offer a Professional Setup migration service you can speak to them on  0800500247 about it. Pro Setup is the name. Even if you just want a chat about options these are the best guys to speak to.


Maybe this will assist anyone having a similar issue.


Sorry about the formatting, was pasted from a word doc and the editor didn't like it very much. If you want a copy of the word doc give the desk a call and they will email it to you.


This will only help if you are migrating to a BT Microsoft 365 product, if you already have a domain with BT and want to unlink it from the mail services then log in to, manage email and deactivate all email addresses associated with that domain. This will automatically remove the domain from the BT Tenant after 1-24 hours so you can add it to your new tenant. If it does not then call the helpdesk 0800800154 and request they remove the domain from CSP for you.


BT can offer fully managed migration with Professional Setup through our Enhanced IT desk on 0800 500 247. 


If you want to go through the migration yourself then this guide will help, BT will still assist with portal access and domain configuration for free.


Please be aware you can only migrate domain email addresses that belong to you, the domain name is owned by BT and is not eligible to be transferred to the Microsoft 365 Exchange platform.


If you consider Microsoft to be an Apartment Complex then a tenant is like an apartment, within the apartment are rooms and personal belongings. A tenant belongs to an individual organization but exists within Microsoft as a whole. You can read more here

A domain name can only exist in one tenant at a time so if your email is already with BT then it will need to be removed from the existing BT Tenant and added to a new Microsoft 365 tenant and the email addresses set up again. The existing emails you have on your PC will need to be imported into the new email account.

This guide will assist you in going through the migration process.

If the following is not suitable for you then this guide may not be suitable and our team will be unable to assist.


  • You must have an existing domain email address, not
  • You use the desktop version of Outlook, not webmail
  • Outlook version must be 2013 onwards
  • We will not assist with 3rd party mail clients like Thunderbird or Livemail but feel free to explore import options yourself.
  • You must be able to access your DNS Records, if the domain is with BT then we can help and explain later in the guide
  • There may be some downtime while the DNS changes are being applied before you add the new mailboxes. This can vary and we cannot guarantee a timescale.
  • Any emails that exist only on mobile devices may be lost. You could forward them to another address if you need to keep them.
  • BT cannot be held responsible for any loss of data through the use of these instructions but we will try and help if there are any issues.




  • BT Enhance IT Support will give you a Microsoft 365 admin user and password that you can log into with
  • You will have to change your password on the first login



  • If the domain is already hosted by BT and part of an existing Microsoft tenant then you will need to go through a process to remove the domain from the tenant. This is done by removing all of the associated domain mailboxes from the BT portal at
    Read this to find out how
    How do I add or remove email addresses for Office 365 Small Business? | BT Business
  • Once all the addresses are removed an automated request is triggered which removes the reference to your domain from the Microsoft tenant, freeing it up for you to add to your new tenant.
  • Once all the associated domain addresses are deleted you can try and add the domain to your new tenant. If this does not work after 2 hours please contact 0800 800 247 and tell them you are going through your own 365 migration and need the domain removed.

You will now be able to do the following:


Once the mailboxes are successfully added to 365 then you can begin setting it up on your computer.


You may have existing email accounts which will not be affected by this process.


Once the new 365 account has been added you can import the mail from the old account. Please follow these guides for assistance.

It may take several hours for the mailbox to fully synchronize depending on how many existing emails you imported.



Office 365 is not just a mailbox, there’s a host of other features available that you can read about here and plenty of training material

Grand Guru

If you only use webmail and have a folder structure built in that then it is still possible to download the structure but it's a manual process and extremely wrist intensive.


You will need Outlook. 


We'll call Outlook on the computer the Outlook app and Outlook on the web we'll call Outlook Webmail.


Setup the account How to set up Office 365 email | BT Business in the Outlook App


Wait until the inbox has downloaded. Create a folder in outlook, call it inbox backup and drag the contents of the inbox to it, inbox in the Outlook App should now be empty.


Now log into Outlook webmail


Delete the contents of your inbox by right-clicking the inbox folder and emptying it, you have it all in the Outlook  App now anyway.


Now you can move onto downloading Outlook webmail folders. Go into your first webmail folder and drag all of the emails into the webmail inbox. You may need to drag it in portions


Once it is all in the webmail Inbox you can go back to the outlook App and send/receive again. This will download all the email from the folder you just moved to the Outlook App inbox.


Wait until it is finished and create a folder in the Outlook App to whatever it was called on the webmail and drag it from the inbox to that folder.


Now go back to the webmail and empty the inbox again.


Do this for all your folders. Downloading through the inbox and rebuilding the folder structure in outlook.


Once you have all you need you can do what you want with the Outlook App PST, import to an exchange if you want.


The Pro Setup guys at BT will do this as part of your migration if you don't want to do it.