I'd pick the telephone and call your favorite congressional rep and ask to speak to the handler of mail. I conducted just such an exercise and learned some interesting factoids.
--All letters are read by staffers reponsible for the subject at hand.
--Personal letter from a zipcode within a reps district are looked at carefully.
--Reps want to hear what their constituents think, not what some advocacy groups thinks. Use your own words and make it clear you think for your self.
--Makes no difference if letter is sent to district office or DC office. I was advised by two reps that if I insisted on snail mail, send it to the district office since snail mail to DC is irridiated. I guess its ok for the staffers in the home office to get anthrax. Anyhow, snail mail, faxes and even emails (if opened in the local office) are overnight pouched to DC. The Big Office sees the mail from the home office the next day.
--Makes no difference if it is faxed, snail mailed, or emailed. Each is printed off and assumes its position in the appropriate pile to be reviewed by the proper staffer.
--Staffers run tallies of for and against <insert flap of choice>.
--Make it one page max.
--Refer to the subject matter at the top of the letter and make it clear so it get to the proper pile.
--Make is succinct, to the point, and leave off Shakespearian pose. State your subject, you position, then shut up.
--Threats impress no one so don't
--Be respectful to the office of elected representative as opposed to a potential scumbag occupying the respected office. Big difference between the two. Honor the office if not the officeholder.
--Multiple forms of the same letter merely increases the workload for the staff and irritates them to no end. One letter is sufficient because it will be tallied and reviewed.
--If using email to communicate, make it just like a letter including complete contact information. They will check to see if you are in their district or state.
--Check with each rep and senator since each has their own preference for where to send letters and in what form. When I lived in NC, Rep Sue Myrick wanted email. Senator Lizzy Dole didn't want email she preferred faxes sent to her district office. Senator John Edwards didn't read communications from little people.
Contrary to what you read on boards, elected reps want to read from the voters. They hold to the time honored rule of each written letter represents 10 unwritten letters. I've been fortunate upon occasion and recieved specific reponses to issues I've raised. Guess it shows me they really do read.