So I sent an email to a list of email ids. I got error message that one id does not exist. Does that mean the email didn’t go to just that one address and went to the others? Or the email didn’t do to anyone? I’m talking about gmail.

Check your sent tab or
Ask Gmail whether they use asynchronous code

Most likely all valid addresses got it

It means that that particular user deactivated/deleted their account and email is no longer valid to receive any emails.

i hope you did not have any attached files to the email, if it didint go you'll have to go through the process of attaching them all again - happened to me last week

Is this the first time you are sending emails?

Gmail sent your email to all except that one email id you provided

I found used gmail to send them, it did go through.

If you used code ti send it, like google scrips, it depends how you did it.

If you did it in a loop and am exception happened, you can guess what happened.

If you added the whole list to the function to send the mail then only the bad one failed.