Buttons in Outlook look wrong

Hello,

The email buttons in Gmail look just fine (as they were created in MailPoet): https://www.dropbox.com/s/u0yh7i6uafopnnb/Botones%20Gmail.png?dl=0.

While the same buttons in Outlook look wrong: the text appears squeezed or clipped: https://www.dropbox.com/s/x04ri6t851aqleb/Botones%20Outlook.png?dl=0

How to improve the presentation of the buttons in Outlook?

Thanks, regards.