The two powerful federal agencies empowered as the whip hand of the Can Spam Act began the process Thursday of fully implementing the United States' first national law aimed at curbing unsolicited bulk e-mail.

Since the Can Spam Act became effective on Jan. 1, it has been criticized as ineffective in slowing junk e-mail. But most of the provisions of the new law are still being interpreted and defined by the Federal Trade Commission (FTC) and the Federal Communications Commission (FCC).

The FTC, for instance, is charged with "defining the relevant criteria to facilitate the determination of the primary purpose of an electronic mail message." The FTC hopes to clarify how to determine whether the law applies to certain electronic messages. In other words, just what is spam, as defined under federal law?

Thursday, the FTC published a notice in the Federal Register seeking public comment on the mandatory "primary purpose" rulemaking and several other spam-related issues as well.

Business isn't waiting around for the FTC. The request for comment followed the first civil complaints filed under the act. On Wednesday, the nation's top ISPs sued hundreds of defendants in Virginia, California, Georgia and Washington state, charging them with sending prohibited bulk e-mails.

The FCC, at its March meeting, issued a series of questions for comment on wireless spam. Specifically, the FCC wants to know whether and how senders will be able to determine whether wireless text is a "mobile commercial electronic message" as defined by the Can Spam Act.

The FCC also wants know if wireless spam should employ an opt-in or opt-out regime (the Can Spam Act dictates opt-out for regular e-mail) and whether there should be a list of, or standard naming convention for, domain names, or an individual registry of wireless e-mail addresses.

"We are not pre-supposing anything at this moment," K. Dane Snowden, head of the FCC's Consumer and Governmental Affairs Bureau, told reporters after the meeting. "We did not make any preliminary assumptions, since there are multiple ways to reach cell phones."

In its Federal Register notice, the FTC says the Can Spam Act gives the agency authority to "expand or contract the categories of messages that are treated as 'transactional or relationship messages' the extent that such modification is necessary to accommodate changes in electronic mail technology or practices."

Currently the law designates five classes of e-mail as transactional or relationship messages that are exempt from the Can Spam penalties for sending unsolicited bulk e-mail. The FTC notice asks if those categories should be expanded.

The FTC is also seeking comments on the possibility of expanding the current 10-day window for processing opt-out requests, "taking into account the interest in allowing consumers to opt out, the interests of recipients of spam, and the burdens imposed on senders of lawful commercial e-mail."

Other questions posed by the FTC for comment include expanding the "aggravated violations" of the law and a clearer definition of the responsibilities and liabilities for forwarding unsolicited e-mail.

"Since the effective date of Can Spam, several issues have repeatedly arisen that potentially may warrant rulemaking. The first of these issues involves a scenario where a sender of a commercial e-mail message seeks to induce recipients to forward the message to friends and acquaintances who, in turn, are urged to forward the message," the Federal Register notice states.

The FTC seeks comment on the legal obligations of senders and recipients who forward messages in such "forward-to-a-friend" situations.

Another emerging issue is when several businesses or individuals could simultaneously be considered the sender of a message. For example, an e-mail message that promotes an upcoming event and also includes advertising from companies sponsoring the event may have multiple senders.

"A common concern regarding this type of message is whether it may be sent to a recipient who has previously opted out from receiving messages from one of the sponsoring companies whose ad is in the message," the FTC writes.

Congress also directed the FTC to develop a national do-not-spam list similar to its popular do-not-call registry. The agency has six months from the enactment of the law to come up with a plan for creating the e-mail registry or else explain to Congress why the creation of such a list is not currently feasible.

For both the FTC and the FCC, the nitty gritty of writing rules and regulations for enforcing the Can Spam Act underscores an old Washington axiom: Congress writes in broad strokes, the bureaucracy fills in the blanks.

Some 60 days after the enactment of the law, the blanks remain many and the answers are still undetermined.