Postageapp mangles Rails' mail object. Shouldn't.

[GBH]

Right now this gems hijacks most of the mail construction. This causes tons of issues with things like previews, interceptors and whatever else Rails is doing (plus comparability with other libraries that do things to email). You can bet that Rails 5 will break this gem again.

Better approach would be to let Rails construct whatever it needs and only catch mail object when there's an attempt to deliver. Then you can disassemble mail object to construct our API call.