[FIX] Do not try to send emails without recipient
[FIX] Do not try to send emails without recipient

OmeGak/indico,ThiefMaster/indico,mvidalgarcia/indico,ThiefMaster/indico,pferreir/indico,DirkHoffmann/indico,mic4ael/indico,mic4ael/indico,mic4ael/indico,pferreir/indico,OmeGak/indico,indico/indico,OmeGak/indico,ThiefMaster/indico,indico/indico,OmeGak/indico,pferreir/indico,DirkHoffmann/indico,mic4ael/indico,indico/indico,mvidalgarcia/indico,mvidalgarcia/indico,indico/indico,ThiefMaster/indico,DirkHoffmann/indico,mvidalgarcia/indico,DirkHoffmann/indico,pferreir/indico