Thanks to you Aeric and DonManfred!!!!
After one hour of tests I have found the solution :
When you send the mail, you have to make the difference beetween
Username of smpt.initialize() versus
email.Mailfrom and
smtp.sender.
The good code is:
dim smtp as smtp
dim user_name as string = "name@site.com"
dim mail_to as string = "mail_to@site1.com"
'init of smtp
smtp.Initialize(smtp.site.com,25 ,user_name , "1234", "SMTP")
' init the mail with alias ' as you had recommended !!!
Dim the_mail_from As String = "Alias name <" & user_name & ">"
' or It's works too :-)
' Dim the_mail_from As String = $""Alias name""$& " <" & user_name & ">"
smtp.MailFrom = the_mail_from
smtp.Sender = the_mail_from
smtp.To.Add(mail_to)
.....
smtp.Send
During my firts tests, I was setting then
Username = "nick name <name@site.com>", it was wrong, the Username of smtp have to be the real mail, and the smtp.sender and smpt.MailFrom the Email formated with the nick name... in fact it's logical!!! ... ohhhhh ! I'm too old for this job
Many thanks to you to bring me on the good way!!