From the AUSTRALIAN copyright organisation's fact sheet for musicians and songwriters...
Things that DON’T make you a copyright owner
There are many myths around about how you can prove you own copyright. Some of the common ones are set out below.
Sending a copy of the work to yourself by registered mail
This is a widely held belief among musicians. Sending copies to yourself, whether by ordinary or registered post, has no legal effect whatever. At most, doing this may prove that the material existed at a particular date: it does not create copyright, and does not make you the copyright owner.
Putting the “copyright notice” on material
A copyright notice (in forms such as “© Dee Rummer 2006”) does not alter the copyright status or ownership of the material. Material that meets the requirements for copyright protection is protected whether or not the copyright notice is used.
You may put the copyright notice on your work yourself – there is no formal procedure. For example, you can hand write, type or stamp the copyright notice on music and lyrics that have been written down, and on recordings of the music (including on demo tapes).
The purpose of the notice is to let someone seeing it know that the material is protected, and that the person named claims to be the copyright owner. It can also be helpful if someone wants to use your work, as it gives them somewhere to start when they are trying to find the copyright owner. Since it does not change the copyright status of the material, the wording of the notice is not crucial. Nonetheless, it is a good idea to use the notice, or similar wording,
on material you create.