I own a group and invited 6 people recently and 1 of them received the email invitation and the other did not?

Question

I own a group and invited 6 people recently and 1 of them received the email invitation and the other did not?

Answer 1

some mail providers sees invites as spam, and block them. invites themselves have been glitchy for years anyway.

if you have a closed / invite only group, you can see if the other 5 have a different address to send them to.

if it's not a closed group, send the URL to them- located in the web browser while you're on the group, copy and paste that to an e-mail and send it. it wont be seen as spam, they click the link, and see top right Join This Group-

Answer 2

Most likely you miss-typed them. Look at the example but also look at the Invite help.