Other members of the community, especially members of the welcoming committee, can then focus on checking contributions by new authors, and new userpages, and leaving personalized messages, aiming to be helpful and encouraging.
streamlining the standard welcome tasks, and freeing up community volunteers/interns to do more individualized work. See Appropedia:Welcoming committee.
Note if we encourage users to register their emails, they'll actually get notified (by default?) that the message has been left - important for helping people stay connected.