I'm not sure why this service really even raises eyebrows. Dynamic DNS has
been around for many years, so it's always been possible to host your own
email. Admittedly, Own-Mailbox makes the process of doing so (potentially)
trivial even for those not technically inclined. And as Jookia said, one
should almost certainly be weary of security/crypto that has not seen
rigorous scrutiny.
But I guess the real question is if one really wants to run his or her own
email server? And what protections does one seek from OM that aren't
currently addressed by existing mail services? My sense is that any
protection currently afforded by hosting/storing your own email on your own
equipment rests on the premise that such emails are legally your property.
But this is a legal protection, which only means it potentially limits what
can be admitted as evidence in the courts, and nothing more. Technically,
there is a lot that can go wrong here, and the OM user is utterly dependent
on the expertise of OM to configure his equipment correctly/securely without
any real assurances they have done so. (After all, if you have the expertise
to test the security of their equipment, then you probably are sufficiently
competent to not really need what they are offering, yes?)
Personally, I think one remains better off--both legally and technically--to
"outsource" your email to a proper email service located outside your
country's borders. Preferably, one that genuinely cares about the data and
privacy of their users.
