Open your HTML email signature file in your web browser.
Press Ctrl + A to select the entire email signature, then press Ctrl + C to copy it.
IMPORTANT: Do not use your mouse to select the area, only use Ctrl + A as you may miss out on grabbing some of the code.
Switch to Outlook 2019 and click File at the top left of your toolbar, then select Options.
Select Mail from the sidebar and click the Signatures… button.
Click New and enter a name for your email signature, press OK.
Click inside the signature editor and paste your copied signature by pressing Ctrl + V.
NOTE: Your email signature may not display correctly in the signature editor. This is normal and is due to the small size of the window. Your signature will display correctly when you compose a new email.