pmail, send mail using Postmark from the command line.
Install by running
$ gem install pmail
pmail will look for a YAML file located in ~/.pmail which can be used to specify any of the parameters that pmail takes.
This is most useful for specifying your Postmark API key and sender signature. For example:
--- :api_key: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX :from: Ben Ubois <firstname.lastname@example.org>
$ pmail -t email@example.com -s Subject < message_body.txt