Yes, getting all my contacts notified and changed is a hassle 
I have contacts who changed their email and for some reason when i message them their old email will come up and if I am not watchful message will not go to the proper email.
Not sure why the old address comes up since I have removed it from contacts but it is till hanging around somewhere in the system and I have not found yet.

There are some messages I will be glad to leave behind but others that only use the address on rare occasions that I am at risk of forgetting to update.

Will need a few rainy days to work through what has accumulated for 30 or more years.