What's the maximum number of addressees on a Gmail? Hitting the limit? or Does Gmail have a maximum n

500 is the max, but don’t push it. Gmail’s algorithms are weird—sometimes they’ll block you way before that.

I’d recommend splitting your list and sending over a few hours. Or just use a proper email service like MailerLite.

Side note: If you’re sending to a work list, check if your org has its own rules.