Here is in interesting fact about official Town Council Emails….
At its simplest, it isn't a breach of GDPR. - Public sector emails are fully subordinate to an FOI request, you must assume everything you write can / may end up on the front page of your local paper. [ Disclosure, part of my day-job is GDPR - and stopping businesses from claiming 'GDPR!!', every time they refuse to do something ]
Quoted from the Councillor Q&A web site