PDF Files change fonts when emailing
I have specialty fonts that I have saved in some documents to email. On my new laptop (M1, 2020, Big Sur) they open fine in Adobe Acrobat Reader DC, but when I attach them to an email, the specialty font defaults to a wonky, odd symbol look. How can I fix this? I've checked every preference. (Doesn't do this on my old, slowly dying Mac-- mid 2012, Yosemite.
MacBook Pro 13″, macOS 11.2