Add the ability to impersonate a subuser

[thinkingserious]

Please see the Python implementation for an example.

[stianpr]

Would be nice to get this in. We currently have to extend the SendGrid class to add the on-behalf-of header. And the documentation is clearly wrong because it states that one has to prefix the username with subuser_ which doesnt work. One only need to add the username to that header. So the documentation should be fixed also.

[thinkingserious]

Hi @stianpr!

Agreed! I can't wait until this reaches the top of the backlog.

[Jericho]

@stianpr I asked about the "subuser_" prefix and I was told that it's necessary. Your experience seem to indicate that it's not the case so I'm a little confused.

@thinkingserious It would be great if you could settle this question once and for all: is the subuser_ prefix necessary or not?

[stianpr]

@Jericho @thinkingserious Well, during my testing and implementation of this it only worked without the subuser_ prefix. It would be nice to clarify this and fix the documentation (or the API) so that we know what to use.

[thinkingserious]

@stianpr @Jericho,

You would replace subuser_ with the actual subuser name.

In our documentation (https://sendgrid.api-docs.io/v3.0/how-to-use-the-sendgrid-v3-api/on-behalf-of) we will be updating on-behalf-of: subuser_<username> to read as on-behalf-of: <username>.

Thanks!