I have created a form to collect emails of people who want to opt out of certain, one-off promotions (like Mothers’ Day) thinking that I could then select the list that collects submissions when creating the campaign, using the ‘do not send’ section.

But, I realise the submitted email addresses will still be on our main list(s) that we will be sending the campaign to. If an email address is on both a list/segment you are selecting to send to, and one you are selecting not to send to, does the campaign get sent to the email address in question, or not? Which overrides the other in this instance?