We have a few domains that are subscribed with operator@ and unfortunately one of my colleagues unsubscribed to the renewal emails this morning.
Because of the vast number of subs - we can't simply change the email address. Would it be posisble to remove us from a blacklist to ensure we receive these emails again please.
Welcome to the Let's Encrypt Community! 
You can just resubscribe and put "+whatever" before the @ sign in the email address. Let's Encrypt will treat this "plus address" as a different email address even though it will be delivered to the same email box. Your email provider might deliver these emails to a "whatever" folder under your inbox.
That's not a Let's Encrypt thing, just a feature of many, but not all, email services. (My personal postfix/dovecot are configured to use - rather than +, and I don't think the Exchange/Hosted Outlook ecosystem has an equivalent at all, last I checked.) Email services that don't support it will just see operator+whatever@ as a mailbox that doesn't exist.
Then some email testing/verification would be in order prior to making any change.
Send to:
oldname-random@domain
oldname+random@domain
See if any get to your inbox.
Just echoed the advice from here: 
Oh, I know. that page just says "many common email services treat" it that way, whereas the way you phrased it sounded to me like Let's Encrypt might strip off the +whatever when sending email, which I don't think that they actually do.
I tried adding +whatever but it didn't make any changes
Where?