This guide tells you how to put yourself on the raid standby list, which allows you to get EP even if you don't get an invite.

About
Those that are online during a raid (whether they have signed or not) can opt to be put on standby. Standby Raiders will get full EP awards even if they are not inside of the raid group but MUST be available until the scheduled raid end. To be on this list you obviously need to be the correct level, have the required gear and be ready to join the raid group at a moments notice if the need should arise. If you are on the standby list and are asked to join the raid and you cannot, or you join and you are not prepared or leave early then you will loose all EP earned that night along with the privlege to use standby EP for a period of time (see EPGP - Awards, Penalties & Constants).

Sounds Great, How?
To enable stand-by EP, you need to whisper the raid ML (normally the RL)  the following (the /w is case sensitive);

/w Trickylion epgp standby

Additionally if you are available but on one of your alts you can use the whisper (assuming your alts name is millicent);

/w Trickylion epgp standby millicent