(VB.NET UWP/WinRT) MailMan GetBadEmailAddrs

Demonstrates how to get the email addresses flagged as invalid during an SMTP send.

Note: An SMTP server can only issue errors for email addresses under it's own domain. For example, if using smtp.gmail.com to send email, the GMail server can only know what emails in the gmail.com domain are invalid. If, for example, the "TO" recipient is "doesNotExist@chilkatsoft.com", then the email would be accepted. If it's not actually a valid email address, it is not flagged as an error during the client-to-SMTP-server conversation. (If the email address turns out to be truly invalid, then a DSN (Delivery Status Notification, or "bounce") email *might* be sent by the final destination mail server to the return address.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' Demonstrates how to get the list of invalid email addresses flagged by the SMTP server
' at the time of sending (i.e. during the SMTP conversation).

Dim mailman As New Chilkat.MailMan

mailman.SmtpHost = "outlook.office365.com"
mailman.SmtpPort = 587
mailman.StartTLS = True

' Set the SMTP login/password
mailman.SmtpUsername = "OFFICE365-SMTP-LOGIN"
mailman.SmtpPassword = "OFFICE365-SMTP-PASSWORD"

' Create a new email object
Dim email As New Chilkat.Email

email.Subject = "Testing for Chilkat API..."
email.Body = "Testing for Chilkat API..."
email.From = "Chilkat Support <my-office365-user@mydomain.com>"
Dim success As Boolean = email.AddTo("Chilkat Admin","admin@chilkatsoft.com")
success = email.AddTo("Non-Existent Recipient 1","nonexist1@something.com")
success = email.AddTo("Non-Existent Recipient 2","nonexist2@gmail.com")
' To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

' Allow SendEmail to succeed even if some recipients are rejected immediately
' by the SMTP server.
mailman.AllOrNone = False

' Call SendEmail to connect to the SMTP server and send.
' The connection (i.e. session) to the SMTP server remains
' open so that subsequent SendEmail calls may use the
' same connection.  
success = Await mailman.SendEmailAsync(email)
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


success = Await mailman.CloseSmtpConnectionAsync()
If (success <> True) Then
    Debug.WriteLine("Connection to SMTP server not closed cleanly.")
End If

Debug.WriteLine("Mail Sent!")

' IMPORTANT:  This example uses the Office365 SMTP server.  However, Office365 does not 
' reject any invalid emails, even for it's own domain.  This is common behavior.
' The same is true for GMail.  In many cases, the recipient email addresses are silently
' accepted by the SMTP server, even if known to be invalid.   

' Using GetBadEmailAddrs would only make sense for server that explicilty rejects local recipients
' known to be invalid.

' Examine which email addresses were rejected by the SMTP server during the SMTP conversation. 
' (i.e. during the SendEmail)
Dim badAddrs As Chilkat.StringArray = mailman.GetBadEmailAddrs()
Dim numBadAddrs As Integer = badAddrs.Count
Dim i As Integer = 0
While i < numBadAddrs
    Debug.WriteLine("Rejected recipient " & i & ": " & badAddrs.GetString(i))
    i = i + 1
End While