Steve on 14 Oct, 2019 02:33 PM
welcome to the GPGTools support platform. Sorry you are having problems using GPG Suite.
GPG Mail on macOS 10.12 and newer does not support the PGP/Inline format. As a workaround for recipients relying on that undocumented format, you could use GPG Services: KB explaining how to encrypt and sign text or files
Can you share some information as to the setup not accepting PGP/MIME or in the specific case no attachments at all?
GPG Mail defaults to the only standard there is for sending OpenPGP Emails, which is PGP/MIME. The format you are referring to, is called PGP/Inline and is an undocumented non-standard format. That leads to several problems, thus we default to PGP/MIME.
While PGP/MIME allows to encrypt attachments, OpenPGP/Inline currently does not. Also, you are limited to text only. Any formatting will be ignored.