Note: Make sure you are using either Google Chrome or Firefox during the installation process.
Create your email signature on NEWOLDSTAMP.com and follow these simple steps to install it in FastMail.
After you finish creating your email signature, click Save and Install button under the signature preview.
Or if you have saved your signature priorly, hover over your signature on the Dashboard and click Use button.
Select the option Other in the list of email clients.
Scroll down the Signature Preview and Click the Copy and Proceed button, which will save the signature code in the clipboard.
Go to FastMail on the upper left corner click the arrow pointing down and choose Settings.
You will see a list of your accounts. Use the Edit button to access the signature for each account
Paste the signature in the signature block and Save changes.
Compose a new email and watch the magic happen.
Congrats! Now you can use your email signature in every email in FastMail.