39 € per year.
That said, that includes your own domain. But I think if you register with the average registrar (eg Gandi.net) you can have a mailbox with own domain for less money?
Positive is that they rely on green energy (but they're not the only ones to do so, Posteo for example does as well if I'm remembering correctly) and for me the Dutch language (my mothertongue) support would be a bonus.
I do feel though that there's cheaper options that offer the same package in terms of privacy and own domain...