
Sadly Microsoft Outlook for Mac does not allow HTML email signatures but there is a solution — an additional plugin by element26 for $2.99 which adds the ability to install a Mirosign HTML email signature on Microsoft Outlook for Mac 2011, 2016, 2019 and 365.
We do recommend using alternative mail programs for Mac if you require a good looking email signature. Try using Mac mail native email app or Spark mail instead.
Step 1 — Create your signature
Create your email signature in Mirosign.com.
Step 2 — Install HTML Email Signature plugin
Purchase and install HTML Email Signature – Outlook for $3.99

This is an independent third-party plug-in that allows html email signatures to be added to Outlook for Mac. After a recent update we have had slight problems with the email signatures displaying in google app on iPhone after sending from Outlook for Mac with this plugin.
Step 3 — Open Outlook for Mac signature settings
Open Outlook for Mac
Select New Email.
Select Signature > Signatures.
Select + and type a name for the signature called “Mirosign.com”

Step 4 — Copy HTML signature code
Return to Mirosign.com in your browser window
Click the yellow ‘Copy HTML’ button.

Step 5 — Paste HTML signature code
Paste the email signature in this box and click ‘Create signature’

Under New messages, select your signature.
Select the red circle in the upper left to close.
Select New Email to see the signature you created.