What does this logentry mean

Hello!

Found the following in the INFO log:

2008.10.09 09:25:50 Registered user11@jabber.mydomain.com/spark as nick66@somedomain.com in rosterless mode.

jabber.mydomain.com is our OF server here

user11 is a valid user

nich66@somedomain.com I never heard of

What does this mean???

Bye

Starry