Fix AlphaMail support

Hi,

I had a talk with the guys at AlphaMail. They are currently migrating their code to a new API version, but only one function currently work: send mail.

Basically we have two solutions for this provider: either use /v2 but only one method, or currently use /v1 until they port all their code to /v2. The guy there told me it may be a better idea to use /v1 now, so that everything work for SlmMail users.

This PR does use /v1 and fix the send mail, so AlphaMail is now completely functional.