Send an email to my client if I void a credit card charge. Sometimes I accidentally charge their card and if they got an email that I voided it, then it would save from them calling me.
For clients who opt to receive automated emails when their credit card is charged, I suggest that they also receive automated emails when a charge is voided.
Sometimes, I accidentally charge a card when, for instance, the client actually paid by check or isn't responsible for the full fee. I immediately notice and void the charge but the client is only notified of the charge, not of the void. I then have to send them a personalized emailing explaining that their card was accidentally charged but voided, etc. It'd be easier if they were automatically notified.