Several online resources point to these two articles at Campaign Monitor:

• Using web fonts in email (Dec. 2012)
• Web Fonts (permanent resource)

The first link provides examples on how to do this, while the second one has informaiton about email client support & compatibility with this feature.

Keep in mind using web fonts will have a limited effect if viewing such emails while offline.

This older MozillaZine article also has information about fonts use in Thunderbird. In my experience in most cases the receiving party will have to have the fonts locally installed for the best results.

Hi Fabian,

Thank you very much for your reply! I found these pages as well, however I do not know where to put the code, since I don't know how to change the header.

I also read that it might not be smart to want to do this because some providers might label the email as spam if you do change the header.

Do you have any advice or experience with this matter? And do I want to put so much time and effort into this if many email providers do not support it?

Thanks for your time!

It would be useful if you linked the articles you found before when you write. If I knew you already read about this, I would not have spent time searching for you.

The articles I linked to are pretty detailed. I doubt this would trigger SPAM detection, though - this is just my opinion of many years dealing with SPAM.

About your last question, well, only you know why you would need this in the first place. It took many years for people (and email clients) to even consider using HTML, fonts are another component of that discussion (ie. content vs. container/presentation). I personally don't like to receive emails with too much formatting.

Thank you Fabian, for your time and efforts!

I'll post the pages I read for new questions in the future. I can Imagine this saves guys like you time.

I'll keep my e-mails as they are for now.