A large number of people sending out newsletters have a tendency to put everyone on the to: or cc: which is a GDPR violation. Well unless you have their explicit permission for that which is highly unlikely.
Not wishing to undermine the importance of the point, but any violation depends on the scope (i.e. is the newsletter a personal update or an update from a formal or informal organisation). For example, quoting from an internet report copyright University of Gottingen
, " . . . the GDPR does not regulate the processing of personal data that natural persons carry out as part of purely personal or household activities, for example, correspondence and social networking." It is not necessarily a GDPR violation (although not necessarily best practice) to use to: or cc: rather than bcc:
In the case of the blocked e-mails that started this thread, I use bcc: as a matter of best practice but I would assume that an update about an informal competition among a group of social acquaintances would fall outside the GDPR regulations.