Redmine

Hello,
Due to some restriction in SMTP server, we need to restrict mail notification more than 100 users.
But if any project has more than 100 members, while notifying all the members, no notification mail sent to any member.
So we need to restrict adding members to a certain limit. is there any way to do that?

another query is that is there anyway to create "Tracker/s" for certain projects only? I mean among 10 different trackers, we need to make 3 trackers only for certain project.

thanks in advance.