So your boss just jumped in, because he remembered that things need to be GDPR-compliant within the next few hours...
And of course he forgot to send the necessary mailing to your newsletter-subscribers.
And of course it's all properly documented in a haphazard mix of excel-files (each of which has a different layout),
text-files, v-cards and the like...
So now you need to extract those email addresses from all those files, because doing it manually will never finish in time.