Check_MK Werk 7414: mail: fix bug with multiple recipients and synchronous delivery

ID: 7414 Title: mail: fix bug with multiple recipients and synchronous delivery Component: Notifications Level: 1 Class: Bug fix Version: 1.6.0i1 If Email notifictations were sent to multiple recipients and synchronous delivery via SMTP was used mail servers may process the recipients of Emails wrong. This may result in failed notifications or only partially delivered Emails. The exact behaviour depends on the mail server.