Character encoding in Mac Mail program

Hi,

I am using Mailpress to send out French posts in a mailing. For some reason, anyone using the Mac Mail program sees garbled characters where there should be accented characters.
The templates are encoded in UTF-8, the database collation is UTF-8, I’m not really sure what I can do on my end to remedy the problem with a specific mail program, but has anyone come across this before?

Thanks,
cori

https://www.ads-software.com/extend/plugins/mailpress/