static string GetMailFromCommand(MailboxAddress mailbox, SmtpExtension extensions) { if (extensions.HasFlag (SmtpExtension.BinaryMime)) return string.Format ("MAIL FROM:<{0}> BODY=BINARYMIME", mailbox.Address); if (extensions.HasFlag (SmtpExtension.EightBitMime)) return string.Format ("MAIL FROM:<{0}> BODY=8BITMIME", mailbox.Address); return string.Format ("MAIL FROM:<{0}>", mailbox.Address); }