Group messages
How do I stop group text messages from an email account?
iPhone 8, iOS 15
Question marked as
Top-ranking reply
Hi chipgriz,
Welcome to the Apple Community.
Apple Support has an article online (link below) that may help:
"Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch"
Says:
From the Phone app, tap Recents, then tap the Info button 
next to the phone number or contact that you want to block.
Scroll down, then tap Block this Caller.
From the Messages app,
open the conversation, tap the contact at the top of the conversation.
Tap the info
button, scroll down, then tap Block this Caller.
From the Mail app,
open the email that has the contact that you want to block,
then tap the contact at the top.
Tap Block this Contact
Complete article: https://support.apple.com/en-us/HT201229
All the best :-)