Email notifications not formatting correctly

For some reason, when email notifications are being sent out from our test instance, they’re not formatted correctly in the receiver’s email-box. The relevant information can be read, but the formatting is all over the place.

Has anyone else had this problem? We’re using mandrill as an emailer, if that makes any difference.

By the way, where in the mastodon directories can the files be found for the email design, if we want to edit it to add in our instance logo below everything else that is sent out in emails?

Thank you very much!