This article deals with migrating an email account(s) from Outlook 2010 to Office365.
It also advises on how to ensure that the Daylite Mail Assistant appears on the right hand side again.
If your emails have stopped working in Apple Mail it is because your email account has been migrated from the old Outlook 2010 to Office365 which now requires 2-factor authentication.
You will need to upgrade to macOS Mojave (10.14), remove the old account and add the new one.

Upgrade to macOS Mojave
If your computer has got an older operating system such as Sierra (10.12) or High Sierra (10.13), it will be necessary to upgrade to Mojave (10.14).

  • Go to your Applications Folder in the finder
  • Look for “Install macOS Mojave” in the list and double-click it
  • This will guide you through the steps required to update too Mojave.
  • It should take about 45 minutes.
  • Once installed you can proceed with the instructions below.

Remove an existing email account

  • Quit Apple Mail.
  • Go to System preferences and choose Internet Accounts.
  • Select the account that you want to remove.
  • Look for the “+” and “-” boxes at the bottom of the list.
  • Press “-” to remove an email account.

Adding an email account

  • Make sure you are signed into any required security first.
  • Open Apple Mail.
  • Go to Apple Mail Preferences
  • Select “Accounts”.
  • Look for the “+” and “-” boxes at the bottom of the list.
  • Press “+” to add an email account.
  • Choose the email service that you use. If Office365 then select Exchange.
  • You will then be guided through the setup.
  • Choose the auto-configure option
  • Sign in using your email address and email password
  • If required, enter the code from your phone or fob for 2-factor authentication.
  • If successful, you will then be presented with a list of features for the account.
  • Untick all options except Email and press continue.
  • Once completed you will start to see emails coming down including your online folders.

Configuring signatures
with the email account setup, it will be necessary to re-connect your pre-exiting signature(s).

  • Go to Apple Mail Preferences Panel and choose Signatures.
  • Select the required signature from the list in the centre
  • Drag the signature on to the newly created account in the list on the left
  • Select the email account on the left and look at the drop down at the bottom on the pane
  • Select the available signature so it is the default used with the email account.

Defining the default email account to use for sending new emails
Apple Mail defaults to automatically selecting the best account for sending all new emails.
However this can be a problem if you have more than one email account – For example it may not be desirable to be sending emails from a personal account.

  • Go to Apple Mail Preferences Panel and choose Composing
  • Look for the option that says Send new messages from:
  • From the drop-down, choose the email account that should be used for sending new emails.

Setting up Daylite Mail Assistant again (DMA)

  • Go to Apple Mail Preferences Panel
  • Look for the section called General
  • You should see a box at the bottom Manage Plug-ins… select it
  • Tick the little box to the left of the words DayliteMailAssistant.mailbundle
  • Apple Mail will restart and you should then see the DMA panel on the right after it starts up again.