I currently have the Thunderbird email client on my Mac, which my business email goes to. Is there anyway of sending mail from my mail server to Office365 as well as Thunderbird? I'm not talking about re-directing from Thunderbird, but actually sending from a mail server to two mail clients. I assume this isn't possible?


1 Answer 1


1. Use IMAP in Thunderbird: By using IMAP (vs. POP), you will be able to setup multiple email clients with the same email address. Messages are stored on the remote email server, rather than the client PC. This makes Thunderbird leave the messages on server to be accessed by 365.

2. Add additional email account to Office365 Portal:

  • Open https://portal.office.com and login with a Office 365 account.
  • Click the cog (gear) in the top-right to change settings
  • Select "Mail" under "Your App Settings"
  • On the left, under "Options" select "Accounts" > "Connected Accounts"
  • Configure your account information as you did in Thunderbird

Here is some additional information on IMAP vs POP

  • When I follow those steps and then click the '+' symbol to add an account I get this message – The address "[email protected]" is the email address of your account, or a proxy address that points to your account You can't create a connection to your own account. (I've used a dummy email address here, but used my actual one when I followed the process).
    – pjk_ok
    Mar 20, 2018 at 14:48
  • Are you already able to view that account's mail in the mailbox? If so, you do not need to add another account. You can already use Office 365's web access and Thunderbird interchangeably if you've already set up Thunderbird to use IMAP. The steps in part 2 are only if you want to use another, non-Microsoft managed account via the Office 365 portal (e.g., gmail, hotmail, etc.).
    – user881561
    Mar 20, 2018 at 15:21
  • I clicked on the Outlook icon in the control panel and my old emails are there up until Nov 2017, which is when I moved over to Thunderbird. My assumption has always been you can't have mail from a mail server go two mail clients which is kind of what I'm seeing now?
    – pjk_ok
    Mar 20, 2018 at 15:29
  • This is true when using POP. If you switch to IMAP in Thunderbird (look in account settings), receiving messages in Thunderbird does not remove them from Office 365 web access. No changes are needed in the Office 365 account. There are other advantages, like syncing sent messages between 365 and Thunderbird. Both methods of accessing emails have the same ability to make changes on the mail server.
    – user881561
    Mar 20, 2018 at 15:38

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