[ryanl0l]

The method of delivery doesn't really have any bearing on the validity of the subpoena, however with some methods it may be easier for the recipient to fraudulently claim that they didn't receive it.

I'm sure they'll use alternate methods if the emails are ignored.

[sk5t]

Service of process is regulated at the state, and sometimes local, level. For you to assert that email is a generally valid method requires some evidence.