Email rendering issues

Hello,

I recently used your plugin to send out an email notification for a new blog post. Unfortunately, the email rendered in a really bad way for many of my clients. The headline was displayed in a length of 2 letters next to eachother stretching over the length of the screen and there were also odd spaces inserted in the words themselves.

Please advise on what I should do to fix this as I cannot send emails like this out to clients.