Allowing a user to opt out of autoresponders

I searched through to see if anyone brought this up but came up blank. We get complaints from our constituents - mostly those who take a lot of online actions - that they receive too many emails and do not want or need to receive an email after they've taken action.

Other than disabling the autoresponder on the whole alert, is there a way to allow a user to opt out of recieving alert autoresponders. My guess is, no. If not, is there a workaround for it? We don't want to upset our super activists who want to take action with us, but do not want to be bombarded with emails after they do so.

Any input is appreciated, thanks!