GMime is a C/C++ library for parsing and creating messages using the Multipurpose Internet Mail Extension (MIME). This is GMime-2.6 which installs in parallel with GMime-3.0 (port gmime3).
To install gmime, run the following command in macOS terminal (Applications->Utilities->Terminal)
sudo port install gmime
To see what files were installed by gmime, run:
port contents gmime
To later upgrade gmime, run:
sudo port selfupdate && sudo port upgrade gmime
Reporting an issue on MacPorts Trac
The MacPorts Project uses a system called Trac to file tickets to report bugs and enhancement requests.
Though anyone may search Trac for tickets, you must have a GitHub account in order to login to Trac to create tickets.