Not certain if this is a known bug or not, but there seems to be a problem with the saildocs request validation for Grib requests that span the dateline.
A request that is properly generated by the plugin as:
Upon hitting "Send", the following validation error message is presented:
"Error! Max Lat lower than Min Lat or Max Lon lower than Min Lon!" This error message prevents you from generating an email
This is OpenCPN
v4.0, running on Win7.
Let me know if you need any additional info.