even as I unchecked in System integration "Always check to see if Thunderbird is the default mail on startup" I always get the message, when I start Thunderbird. I might understand this behaviour at commercial companies, but not at non-profit organisations. At my office computer I need to use another product for official mails, but I like to use Thunderbird for checking private mails. I might have to choose another email client when I run the risk that by defaulting to Thunderbird I might send business related e-mails from my private account. Best regards Dirk