Send Email without Mail Server

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

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'  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 Chilkat.MailMan()

'  Any string argument automatically begins the 30-day trial.
Dim success As Boolean
success = mailman.UnlockComponent("30-day trial")
If (success <> true) Then
    MsgBox("Component unlock failed")
    Exit Sub
End If


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 (smtpHostname Is Nothing ) Then
    MsgBox(mailman.LastErrorText)
    Exit Sub
End If


TextBox1.Text = TextBox1.Text & smtpHostname & vbCrLf
TextBox1.Refresh()

'  Set the SMTP server.
mailman.SmtpHost = smtpHostname


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

email.Subject = "This is a test"
email.Body = "This is a test"
email.From = "Chilkat Support <support@chilkatsoft.com>"
email.AddTo("",recipient)


success = mailman.SendEmail(email)
If (success <> true) Then
    MsgBox(mailman.LastErrorText)
Else
    MsgBox("Mail Sent!")
End If