It doesn't matter whether the "poor man's copyright is "admissible." (Everything is admissible if a judge decides to admit it.)
Because you don't even get to go to court if the work is not registered with the Library of Congress. At which point you don't need the poor man's copyright, because you've got the real thing.
If you go to a lawyer and say, "The Black Eyed Peas stole my song about eternal human freedom," he or she will ask you, "Is your copyright registered with the Library of Congress, and filed within five years of the date of creation?" And if you say, "Well, er, uh, no... but i mialed this to myself, and it's registered mail and everything..." he or she will say, "Go home and blow your nose. I can't file a copyright infringement suit IF YOU HAVEN'T REGISTERED THE FREAKIN' COPYRIGHT!!!!"
From the Library of Congress:
" Do I have to register with your office to be protected?
No. In general, registration is voluntary. Copyright exists from the moment the work is created. You will have to register, however, if you wish to bring a lawsuit for infringement of a U.S. work." (Emphasis mine)
And to clarify.... registering your tunes with your performing rights organizations (ASCAP, BMI, whatever) doesn't make it "easier" for them to track your royalties... it makes it POSSIBLE. If you don't register your tunes, you get NOTHING.
Well, then can you recommend a good publisher to try?
And you live where? Nashville? Huh. OK. You're in feakking "Music City" for Christ's sake. All this info should be falling from the sky and arriving in your cereal box each morning bro. No offesnse. But if you moved there "to make it", it's all there. Well, other than writing kick azz tunes and finding a good song plugger...along with the other 10, 000 great song writers down there doing the same every day. Good luck.
Actually admissibility is controlled by a fairly uniform set of rules. Admissibility though is not the issue, the "weight" which can be given to a piece of evidence it was makes it crucial. Weight is also a "term of art" in law to the extent that it has been set in precedent through prior legal decisions. "
I can think of at least three high profile cases in which music copyright figured (all three fights over a deceased musician's estate) in which the "mailing" was used as evidence of originality of the work. One of the more famous being the fight over Hank William Sr's "unpublished" work. Eventually the case turned on testate issues, but the evidence concerning originality of the work was key to that particular case. So it is not completely invaluable, but it is definitely NOT the best evidence you're going to have of your ownership/authorship of your work. Spend the money, get it registered.
And no, Garr, you won't be gettin' a bill . . . . . . never have yet have ya?
Promote and Support your local musicians! Buy their CDs and frequent the venues where they play!