There are many things that you can do which will almost certainly NOT lead to being heard by an A&R department !! Yet, many people do them.
For example:
1) Sending in CD's/tapes without permission
2) Sending in CD's/tapes addressed to "A&R Dept." rather than a named person
3) Sending an email to every record company you can think of announcing your music can be downloaded from a specific website
The only way to get heard by A&R is to know them personally or know someone who does. If you're relying on somebody else to get your material heard by A&R then you must ensure that they have the right contacts. The turnover of staff at an A&R department is incredible and it's almost a fulltime job in itself, just keeping up with changes