Hi, @AAdmin3👋 Thanks for your question. You'll need to provide more details in order for the community to assist you.
Are these marketing emails?
Are you using a custom coded template?
If so, can you share how you are adding your custom font? Furthermore, what font is set as the fallback? For example: <span style="font-family: Calibri, sans-serif;">Your Text</span>
Can you clarify what you mean when you say, “we type in calibre”, please? If you are trying to paste in text from an external source into the editor, that will not work and the font won't be respected once the email is sent
When working worth anything outside the default fonts listed here, when creating emails, is challenging and will require testing to see how each email client respects, or not, your choice of custom font.