When I add user to a portal without entering any address information, I get this error message:

ModuleId: 2266
ModuleDefId: 15
FriendlyName: Redigere brukerkonti
ModuleControlSource: Admin/Users/ManageUsers.ascx
AssemblyVersion: 04.00.02
Method: System.Net.Mail.Message.set_Subject
FileName:
FileLineNumber: 0
FileColumnNumber: 0
PortalID: 54
PortalName: ....
UserID: 1
UserName: host
ActiveTabID: 1513
ActiveTabName: Brukerkonti
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: ....
ExceptionGUID: 18260225-f401-4752-96ee-e76e95ce68a7
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
InnerException: The specified string is not in the form required for a subject.
Message: DotNetNuke.Services.Exceptions.ModuleLoadException: The specified string is not in the form required for a subject. ---> System.ArgumentException: The specified string is not in the form required for a subject. at System.Net.Mail.Message.set_Subject(String value) at System.Net.Mail.MailMessage.set_Subject(String value) 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.Services.Mail.Mail.SendMail(String MailFrom, String MailTo, String Bcc, String Subject, String Body, String Attachment, String BodyType, String SMTPServer, String SMTPAuthentication, String SMTPUsername, String SMTPPassword) at DotNetNuke.Modules.Admin.Users.ManageUsers.cmdUpdate_Click(Object sender, EventArgs e) --- End of inner exception stack trace ---
StackTrace:
Source:
Servernavn: ...

If I add address info, the error message does not appear. Is it an error in DNN or is it something I have configured right?

Hans Egil