Hey I'm an employee at shortwave.com (the startup behind this). I totally understand the pessimism - to be totally transparent, this is a marketing campaign to get our name out there.

We're an email company, so why not send "real" mail during the holidays. We're not trying to make money doing this and it's a limited time offer :)

There is really just a couple people with some printer templates, stamps, letters and some hot wax[1].

[1] We ordered a custom wax seal with our logo on it for this (pictures on the website) which I think looks great.

If you go through the process, it seems pretty benign. Looks like the stationary has an ad for Shortwave at the bottom, and it unobtrusively reminds you that it’s a Shortwave service throughout.

I think it’s clever, a marketing stunt like this is memorable and makes me curious about the company sponsoring it. Plus, the cost of acquiring a new lead can be pretty high for many SaaS companies. So Shortwave spending less than a dollar per prospect here isn’t suspicious.