iRule to block\reject connections from Lync client

Thank you for the response Cthulhucalling. I forgot to include that we are trying to reject connection from both Lync and Exchange clients. What do you think of this iRule below?

when HTTP_REQUEST { log local0.debug "Client IP:[IP::client_addr] attempt with user agent :[HTTP::header User-Agent]" if { [ string tolower [HTTP::header User-Agent]] contains "microsoft lync"} { drop log local0.info "Client IP:[IP::client_addr] has been blocked with user agent :[HTTP::header User-Agent]" } elseif { [ string tolower [HTTP::header User-Agent]] contains "microsoft outlook"} { drop log local0.info "Client IP:[IP::client_addr] has been blocked with user agent :[HTTP::header User-Agent]" } else { log local0.debug "Client IP:[IP::client_addr] attempt with user agent :[HTTP::header User-Agent] successful" } }