Email / XGate
The Global Marine Networks mail service is called XGate, and is described in more detail at the GMN site.
While LuckGrib directly supports the GMN Optimizer, there are some satellite device setups which are not supported this way, but which are supported when using the GMN XGate application directly.
If you own an Optimizer and are using a satellite phone to download your data, first try using the Optimizer directly with LuckGrib. If that works, it will be easier and more efficient than using email.
However, if you need, or want, to use the XGate email solution, then read on for how that is done.
XGate is available on both macOS and iOS: