Post announcements with topic showing following details:
Time, country, city, + "festival name" + bands
Subject line has limited amount of text, so focus on important parts if space is limited.
Example how it should NOT be done:
subject: "live gig!!! Noise!!!"
Example how to do it:
subject: 17.4.2010 GER, Leipzig: GENOCIDE ORGAN, PAIN NAIL, THO-SO-AA
and message with further information, link to organizer, link to poster, price, etc.
Organizers or the original poster: Keep messages up-to-date. If cancellations, changes, etc. happen, remember to inform about it.