Every platform you rely on can change its rules overnight. An email list is the only audience you actually own, and events generate it more easily than almost any other business.
You are already collecting it
Every ticket sold captures an email address. The failure is not collection, it is that most organizers never write to those addresses again until the next launch, by which point nobody remembers signing up.
Write between events
Photographs from the last night, an announcement of the next date, something useful about the scene you operate in. Two or three emails between events keeps you familiar, so your launch lands in an inbox that recognises you.
Segment by behaviour
Attended, bought but did not attend, registered but never bought. Those three groups need different messages, and treating them identically wastes the best asset you have.
Give the presale to the list
Make list membership genuinely worth something: first access, better price, guaranteed table. When people see that the list gets the good stuff, they join and they stay.
Collect beyond the checkout
Not everyone who is interested buys immediately. A simple "tell me when tickets drop" form on your event page captures the people who were curious but not ready, and those addresses convert well precisely because they asked.
The door is another collection point most organizers waste. A QR code on the way in or out, offering photographs from the night, gathers addresses from people at their most enthusiastic.
Send the photographs
The email nobody unsubscribes from is the one with pictures of them enjoying themselves. Send it within a few days while the night is still fresh, and put the next date at the bottom.
Clean the list occasionally
Addresses that have not opened anything in a year are hurting your deliverability for everyone else. Send them one honest re-engagement message and remove the ones who do not respond. A smaller engaged list outperforms a large indifferent one.
Mind the basics
A recognisable sender name, a subject line that says what it is, and a working unsubscribe link. Deliverability is a slow thing to lose and a slower thing to win back.