(Visual Basic 6.0) Send Email without Mail Server

How to send an email without a mail server (so-to-speak).

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

' Is it really possible to send email without connecting to
' a mail server?  Not really.

' When people ask 'Do you support sending email without 
' a mail server'?  what they're really asking is: 'I don't
' have an SMTP server, and I want to send email.  I see
' other components available where it's not necessary
' to specify an SMTP server.  Does your component have that
' ability?'  In short, the answer is Yes.  But you need
' to understand some things before you jump in...

' Here's what happens inside those other components
' that claim to not need a mail server:  The component does
' a DNS MX lookup using the intended recipient's email address
' to find the mail server (i.e. SMTP server) for that
' domain.  It then connects to that server and delivers the
' email.  You're still connecting to an SMTP server -- just
' not YOUR server.

' Chilkat provides an MxLookup method where you can lookup
' the SMTP hostname that services any given email address. 
' You would then assign the SmtpHost property to this value.
' Chilkat can then connect directly to the recipient's mail 
' server and deliver the email.

' There are a few gotcha's though...

' First, if you're writing an application that is widely 
' distributed, your app might be running within a network
' that blocks outgoing connections to the SMTP port.
' Earthlink, for example, is one major ISP that does this.
' When you are connected to the Internet via Earthlink,
' your apps can *only* connect to Earthlink's SMTP server
' and will not be able to reach any remote servers.  To send
' email, you must use Earthlink's SMTP as a relay.  This is
' common with ISPs.  So... if your application is coded
' as in this example, it will not work within those networks.
' 
' Second, some SMTP servers will reject unauthenticated
' sessions attempting to send email from dynamic IP addresses.
' You may see this error in your LastErrorText:
' 553-Your attempt to send email to us has been blocked
' 553-because your email server is not currently on that domain's Accepted
' 553-Senders list. To request addition to their Accepted Senders list,
' 553-please navigate with a Web browser to the following URL:
' 553-http://reportrbl.gate2service.com/Whitelist/?IPAddress=67.173.123.150
' 553 See http://www.dnsbl.us.sorbs.net/ (dul)

' In a nutshell, just because you were able to do the MxLookup
' and connect to the recipient's mail server, doesn't mean
' you'll be able to send email -- it depends on the IP address
' from which you're connecting.

' Finally, the DNS lookup is potentially time consuming.
' In addition, you cannot use somebody else's email server
' as a relay, so if you're connecting to smtp.xyz.com, you
' can only send email to email addresses at xyz.com.
' To send email to 3 recipients at different domains means
' making 3 separate connections to 3 separate SMTP servers
' to send the email one at a time.

' The mailman object is used for sending and receiving email.
Dim mailman As New ChilkatMailMan

Dim recipient As String
recipient = "admin@chilkatsoft.com"

' Do a DNS MX lookup for the recipient's mail server.
Dim smtpHostname As String
smtpHostname = mailman.MxLookup(recipient)
If (mailman.LastMethodSuccess <> 1) Then
    Debug.Print mailman.LastErrorText
    Exit Sub
End If

Debug.Print smtpHostname

' Set the SMTP server.
mailman.SmtpHost = smtpHostname

' Create a new email object
Dim email As New ChilkatEmail

email.Subject = "This is a test"
email.Body = "This is a test"
email.From = "My Name <myname@mydomain.com>"
success = email.AddTo("",recipient)

Dim success As Long
success = mailman.SendEmail(email)
If (success <> 1) Then
    Debug.Print mailman.LastErrorText
Else
    Debug.Print "Mail Sent!"
End If