CircleID

All due respect to the ACLU - but yes, someone needs to point out to them that:

The FTC prosecuting can-spam infringements, the DoJ / FBI going after fraudulent or criminal spams - or the various state antispam laws under which spammers can be prosecuted primarily target commercial and/or fraudulent speech. 

Neither of which has much 1st amendment protection.

As for the non commercial free speech that's sent as unsolicited bulk email, ISP spamfilters are quite capable of blocking it, based on their users voting that they havent asked for such speech (the this is spam button etc). 

CAN-SPAM certainly doesn't bar ISPs from taking good faith action to block spam.