[Mailjet]

We get your point. But there are no open source versions of the services offered there. It's not only "software", it's "service".

Example: Textmaster is a marketplace for copywriting & translating. Do you think that they could offer some "debian authors"? No, because they have to pay them, otherwise it would be slavery.

It is logic assign a value to the service that is offered. Tens or hundreds of thousands of businesses pay for these services. What they are paying is the value.

When you issue a coupon to offer free access to a service, you don't write it off as a marketing expense... At least, this is not what we're doing at Mailjet. And I don't think it's possible for anyone to do this, it would make things a bit too easy ^^

Imagine: "Hey friend, here's a coupon for 1000 billion emails, it doesn't matter if you don't use it, just activate the coupon so I can write the value off, this way, there won't be any benefits this year."