When inviting people to join group, is there a way to say anything or is all you can do is put in their email?

For instance, I want to tell people why I'm inviting them to join the group or tell others to please respond since they said they wanted to join but didn't answer the first invitation.

When inviting people to join group, is there a way to say anything or is all you can do is put in their email?
you could send them a regular email with the URL pasted in explaining the group and asking them to join and reply.
Reply:yahoo disabled the text box due to spammers. you can send an e-mail yourself ahead of the invite asking them to respond