Many outlets in the right wing media will have a field day with the name alone.
If one is going to try to occupy the moral high ground the choice of language really matters: you are framing the debate by how you word every single relevant item related to a given project, and which item will have greater visibility than the very name of your project?
By using such a name they are serving in a silver plate the opportunity to malicious, uninformed and naive commentators to badmouth whatever they come up with and that before having put forward a single detailed sentence about the proposal.
DarkMail may sound cool, but from the start is eliciting all the wrong kind of associations, I am sure many parties in the field could be interested to join such an effort, but the DarkMail name alone may put some people off.
The name really should be changed, these battles are difficult as it is, people shouldn't make it unnecessarily harder than it is going to be.
Let me put an example, lets compare these 2 headlines:
"Terrorists confess to using DarkMail"
"Terrorists confess to using PrivateMail"
Look, at the end I know it is the same thing, but while a headline would push many to say "yeah, tell me something new" the other may elicit comments of the kind of "What? That is what I use to email my bank"
I really think that name ought to go.