Correos

Una posible solución puede ser a través de sockets. Prueba con este código, pero no permite poner adjuntos.
Private Enum SMTP_State
MAIL_CONNECT
MAIL_HELO
MAIL_FROM
MAIL_RCPTTO
MAIL_DATA
MAIL_DOT
MAIL_QUIT
End Enum
Private m_State As SMTP_State
'
Private Sub cmdClose_Click()
Unload Me
End Sub
Private Sub cmdNew_Click()
txtRecipient = ""
txtSubject = ""
txtMessage = ""
End Sub
Private Sub cmdSend_Click()
Winsock1.Connect Trim$(txtHost), 25
m_State = MAIL_CONNECT
End Sub
Private Sub Form_Load()
'
'clear all textboxes
'
For Each ctl In Me.Controls
If TypeOf ctl Is TextBox Then
ctl.Text = ""
End If
Next
'
End Sub
Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)
Dim strServerResponse As String
Dim strResponseCode As String
Dim strDataToSend As String
'
'Retrive data from winsock buffer
'
Winsock1. GetData strServerResponse
'
Debug. Print strServerResponse
'
'Get server response code (first three symbols)
'
strResponseCode = Left(strServerResponse, 3)
'
'Only these three codes tell us that previous
'command accepted successfully and we can go on
'
If strResponseCode = "250" Or _
strResponseCode = "220" Or _
strResponseCode = "354" Then
Select Case m_State
Case MAIL_CONNECT
'Change current state of the session
m_State = MAIL_HELO
'
'Remove blank spaces
strDataToSend = Trim$(txtSender)
'
'Retrieve mailbox name from e-mail address
strDataToSend = Left$(strDataToSend, _
InStr(1, strDataToSend, "@") - 1)
'Send HELO command to the server
Winsock1.SendData "HELO " & strDataToSend & vbCrLf
'
Debug.Print "HELO " & strDataToSend
'
Case MAIL_HELO
'
'Change current state of the session
m_State = MAIL_FROM
'
'Send MAIL FROM command to the server
Winsock1.SendData "MAIL FROM:" & Trim$(txtSender) & vbCrLf
'
Debug.Print "MAIL FROM:" & Trim$(txtSender)
'
Case MAIL_FROM
'
'Change current state of the session
m_State = MAIL_RCPTTO
'
'Send RCPT TO command to the server
Winsock1.SendData "RCPT TO:" & Trim$(txtRecipient) & vbCrLf
'
Debug.Print "RCPT TO:" & Trim$(txtRecipient)
'
Case MAIL_RCPTTO
'
'Change current state of the session
m_State = MAIL_DATA
'
'Send DATA command to the server
Winsock1.SendData "DATA" & vbCrLf
'
Debug. Print "DATA"
'
Case MAIL_DATA
'
'Change current state of the session
m_State = MAIL_DOT
'
'So now we are sending a message body
'Each line of text must be completed with
'linefeed symbol (Chr$(10) or vbLf) not with vbCrLf
'
'Send Subject line
Winsock1.SendData "Subject:" & txtSubject & vbLf
'
Debug.Print "Subject:" & txtSubject
'
Dim varLines As Variant
Dim varLine As Variant
'
'Parse message to get lines (for VB6 only)
varLines = Split(txtMessage, vbCrLf)
'
'Send each line of the message
For Each varLine In varLines
Winsock1.SendData CStr(varLine) & vbLf
'
Debug. Print CStr(varLine)
Next
'
'Send a dot symbol to inform server
'that sending of message comleted
Winsock1.SendData "." & vbCrLf
'
Debug.Print "."
'
Case MAIL_DOT
'Change current state of the session
m_State = MAIL_QUIT
'
'Send QUIT command to the server
Winsock1.SendData "QUIT" & vbCrLf
'
Debug. Print "QUIT"
Case MAIL_QUIT
'
'Close connection
Winsock1. Close
'
End Select
Else
'
'If we are here server replied with
'unacceptable respose code therefore we need
'close connection and inform user about problem
'
Winsock1. Close
'
If Not m_State = MAIL_QUIT Then
MsgBox "SMTP Error: " & strServerResponse, _
vbInformation, "SMTP Error"
Else
MsgBox "Message sent successfuly.", vbInformation
End If
'
End If
End Sub
Private Sub Winsock1_Error(ByVal Number As Integer, Description As String, ByVal Scode As Long, ByVal Source As String, ByVal HelpFile As String, ByVal HelpContext As Long, CancelDisplay As Boolean)
MsgBox "Winsock Error number " & Number & vbCrLf & _
Description, vbExclamation, "Winsock Error"
End Sub
Para poner adjuntos busca en esta página que es de dónde he bajado el código. http://www.vbip.com/winsock/winsock_simple_sender.asp
Salu2.