For what it's worth, no matter what incarnation of email addresses I use, this is the description from the scheduler history as to why the notification was not sent.

Event Notification failed.System.FormatException: The specified string is not in the form required for an e-mail address.
at System.Net.Mime.MailBnfHelper.ReadMailAddress(String data, Int32& offset, String& displayName)
at System.Net.Mime.MailBnfHelper.ReadMailAddress(String data, Int32& offset)
at System.Net.Mail.MailAddressCollection.ParseValue(String addresses)
at System.Net.Mail.MailAddressCollection.Add(String addresses)
at System.Net.Mail.Message..ctor(String from, String to)
at System.Net.Mail.MailMessage..ctor(String from, String to)
at DotNetNuke.Services.Mail.Mail.SendMail(String MailFrom, String MailTo, String Cc, String Bcc, MailPriority Priority, String Subject, MailFormat BodyFormat, Encoding BodyEncoding, String Body, String Attachment, String SMTPServer, String SMTPAuthentication, String SMTPUsername, String SMTPPassword)
at DotNetNuke.Modules.Events.EventNotification.SendEventNotifications()
at DotNetNuke.Modules.Events.EventNotification.DoWork()

The error occurs in Mail.SendMail.

I can update the Admin Profile without any error, but the Super User gets it every time.