Send Email in VB 6.0 - Tutorial¶

This tutorial introduces how to send email in VB 6 using SMTP. It also demonstrates SSL, S/MIME, Embedded Images, Email Queue, Multiple Threads, Exchange WebDAV and Exchange Web Service (EWS) usage.

Sections:

Send email in a simple VB6 project using SMTP protocol
Common SMTP Transport Error
TLS 1.2
Where can I get my SMTP email server address, user and password?
Email Address Syntax and Multiple Recipients
From, ReplyTo, Sender and Return-Path
Mail Priority
Troubleshooting
Process Bounced Email (Non-Delivery Report)
Email Tracking
Bulk Email Sender Guidelines
32bit/x64 ActiveX DLL
Distribution

Send email in a simple VB6 project using SMTP protocol¶

To better demonstrate how to send email using SMTP protocol, let’s create a VB 6.0 Standard EXE project at first, then add a CommandButton on the Form, double-click this button. It is like this:

Installation¶

EASendMail is a SMTP component which supports all operations of SMTP/ESMTP protocols (RFC 821, RFC 822, RFC 2554). Before you can use the following sample codes, you should download the EASendMail Installer and install it on your machine at first.

Add Reference¶

To use EASendMail SMTP ActiveX Object in your project, the first step is “Add reference of EASendMail to your project”. Please select menu -> Project -> References -> and select EASendMailObj ActiveX Object, click OK, the reference will be added to current project, and you can start to use it to send email in your project.

[VB 6.0 - Send email - Example]¶

Now add the following codes to the project and change From, To, Server, User and Password to corresponding value. The following example codes demonstrate how to send email using SMTP protocol in VB6 project.

Const ConnectNormal = 0
Const ConnectSSLAuto = 1
Const ConnectSTARTTLS = 2
Const ConnectDirectSSL = 3
Const ConnectTryTLS = 4

Private Sub Command1_Click()

    Dim oSmtp As New EASendMailObjLib.Mail
    oSmtp.LicenseCode = "TryIt"

    ' Set your sender email address
    oSmtp.FromAddr = "test@emailarchitect.net"
    ' Add recipient email address
    oSmtp.AddRecipientEx "support@emailarchitect.net", 0

    ' Set email subject
    oSmtp.Subject = "simple email from VB 6.0 project"
    ' Set email body
    oSmtp.BodyText = "this is a test email sent from VB 6.0 project, do not reply"

    ' Your SMTP server address
    oSmtp.ServerAddr = "smtp.emailarchitect.net"

    ' User and password for ESMTP authentication, if your server doesn't require
    ' User authentication, please remove the following codes.
    oSmtp.UserName = "test@emailarchitect.net"
    oSmtp.Password = "testpassword"

    ' ConnectTryTLS means if server supports SSL/TLS connection, SSL/TLS is used automatically
    oSmtp.ConnectType = ConnectTryTLS

    ' If your server uses 587 port
    ' oSmtp.ServerPort = 587

    ' If your server uses 25/587/465 port with SSL/TLS
    ' oSmtp.ConnectType = ConnectSSLAuto
    ' oSmtp.ServerPort = 25 ' 25 or 587 or 465

    MsgBox "start to send email ..."
    If oSmtp.SendMail() = 0 Then
        MsgBox "email was sent successfully!"
    Else
        MsgBox "failed to send email with the following error:" & oSmtp.GetLastErrDescription()
    End If

End Sub

If you set everything right, you can get “email was sent successfully”. If you get “failed to send email with the following error:”, then please have a look at the following section.

Common SMTP Transport Error¶

When you execute above example code, if it returned an error about “Networking connection/Socket” or “No such host”, it is likely that your SMTP server address is not correct. If it threw an exception about “5xx Relay denied”, it is likely that you did not set user authentication. Another common error is “5xx Must issue a STARTTLS command first” or “No supported authentication marshal found!”, that is because your SMTP server requires user authentication under SSL connection. You can set the SSL connection to solve this problem. You can learn more detail in Troubleshooting section.

TLS 1.2¶

TLS is the successor of SSL, more and more SMTP servers require TLS 1.2 encryption now.

If your operating system is Windows XP/Vista/Windows 7/Windows 2003/2008/2008 R2/2012/2012 R2, and you got connection error with SSL/TLS connection, you need to enable TLS 1.2 protocol in your operating system like this:

Enable TLS 1.2 on Windows XP/Vista/7/10/Windows 2008/2008 R2/2012

Where can I get my SMTP email server address, user and password?¶

Because each email account provider has different server address, so you should query your SMTP server address from your email account provider. To prevent spreading email from the server, most SMTP servers also require user authentication. User name is your email address or your email address without domain part, it depends on your email provider setting.

Finally, if you have already set your account in your email client such as Outlook or Window Mail, you can query your SMTP server address, user in your email client. For example, you can choose menu -> “Tools” - > - “Accounts” - > “Your email account” - > “Properties” - > “Servers” in Outlook express or Windows Mail to get your SMTP server, user. Using EASendMail to send email does not require you have email client installed on your machine or MAPI, however you can query your exist email accounts in your email client.

Email Address Syntax and Multiple Recipients¶

The following example codes demonstrates how to specify display name and email address by different syntax.

' For single email address (From, ReplyTo, ReturnPath), the syntax can be:
' ["][display name]["]<email address>.
' For example:
"Tester, T" <test@adminsystem.com>
Tester <test@adminsystem.com>
<test@adminsystem.com>
test@adminsystem.com

' For mulitple email address (To, CC, Bcc), the syntax can be:
' [single email],[single email]...
' (,;\r\n) can be used to separate multiple email addresses.
' For example:
"Tester, T" <test1@adminsystem.com>, Tester2 <test2@adminsystem.com>,
   <test3@adminsystem.com>, test4@adminsystem.com

[VB 6.0 - Email syntax - Example]

To better understand the email address syntax, please refer to the following codes. It demonstrate how to specify from, to, cc by different email address syntax.

oSmtp.FromAddr = "Tester<test@adminsystem.com>"
oSmtp.FromAddr = "test@adminsystem.com"
oSmtp.FromAddr = "<test@adminsystem.com>"

' Using AddRecipientEx to add To, Cc and Bcc in VB 6.0/Visual Basic 6.0
' Multiple addresses are separated with (,)
' The syntax is like this: "test@adminsystem.com, test1@adminsystem.com"
oSmtp.AddRecipientEx "test1@adminsystem.com, test2@adminsystem.com", 0
oSmtp.AddRecipientEx "Test1<test@adminsystem.com>, Test2<test2@adminsystem.com>", 0

' You can also add carbon copy (CC) or blind carbon copy (BCC) in the email.
oSmtp.AddRecipientEx "CC recipient<cc@adminsystem.com>", 1
oSmtp.AddRecipientEx "Bcc recipient<bcc@adminsystem.com>", 2

From, ReplyTo, Sender and Return-Path¶

From, Reply-To, Sender and Return-Path are common email headers in email message. You should always set From property at first, it is a MUST to identify the email sender. The following table lists the header and corresponding properties:

Header	Property
From	Mail.FromAddr
Reply-To	Mail.ReplyTo
Sender	Mail.Sender
Return-Path	Mail.ReturnPath

From

This property indicates the original email sender. This is what you see as the “FROM” in most mail clients.
Reply-To

This property indicates the reply address. Basically, when the user clicks “reply” in mail client, the Reply-To value should be used as the recpient address of the replied email. If you don’t set this property, the Reply address is same as From address.
Sender

This property indicates the who submit/send the email. When the user received the email, the email client displays: From: “sender address” on behalf of “from address”. If you don’t set this property, the Sender address is same as From address. Sender property is common used by mail listing provider. This property also takes effect to DKIM/DomainKeys signature, if Sender is different with From address, then you should sign DKIM/DomainKeys based on Sender domain instead of From address domain.
Return-Path

This property indicates the delivery notification report address. If you don’t set this property, the Return-Path address is same as From address. This property also takes effect to SPF record, if Return-Path is different with From address, then remote SMTP server checkes SPF record of Return-Path instead of From address.

[VB 6.0 - From, ReplyTo, Sender and Return-Path in Email - Example]

The following example codes demonstrate how to specify From, Reply-To, Sender and Return-Path in Email. With the following example codes:

If the email couldn’t be delivered to recipient, a non-delivery report will be sent to report@emailarchitect.net.
If the user received the email, the email client will display: sender@emailarchitect.net on behalf of from@adminsystem.com.
If the user click “reply”, the replied email will be sent to reply@adminsystem.com.

' [VB, VBA - From, ReplyTo, Sender and Return-Path]
Dim oSmtp As New EASendMailObjLib.Mail
oSmtp.LicenseCode = "TryIt"
oSmtp.FromAddr = "from@adminsystem.com"
oSmtp.ReplyTo = "reply@adminsystem.com"
oSmtp.Sender = "sender@emailarchitect.net"
oSmtp.ReturnPath = "report@emailarchitect.net"

'[VBScript, ASP - From, ReplyTo, Sender and Return-Path]
Dim oSmtp
Set oSmtp = Server.CreateObject("EASendMailObj.Mail")
oSmtp.LicenseCode = "TryIt"
oSmtp.FromAddr = "from@adminsystem.com"
oSmtp.ReplyTo = "reply@adminsystem.com"
oSmtp.Sender = "sender@emailarchitect.net"
oSmtp.ReturnPath = "report@emailarchitect.net"

Mail Priority¶

If you want to set Higher or Lower priority to your email, you can use Priority prority

[VB 6.0 - Mail Priority - Example]

' Set high priority
oSmtp.Priority = 1 'High priority

Troubleshooting¶

When you send email in above simple VB project, if it returned an error, please have a look at the following tips:

“No Such Host” Error¶

This error means DNS server cannot resolve SMTP server, you should check if you input correct server address. If your server address is correct, you should check if your DNS server setting is correct.

Common “Socket/Networking Connection” Error¶

This error means there is a problem with networking connection to SMTP server. You can use Windows built-in Telnet command to detect the networking connection.

Using Telnet to detect networking connection to SMTP server¶

Note

Notice: in Windows 2008/Windows 8 or later version, Telnet Client is not installed by default, you should enable this command in Control Panel -> Programs and Features -> Turn Windows feature on or off -> have Telnet Client checked.

Under DOS command prompt, input “telnet [serveraddress] [port]”:

telnet mail.emailarchitect.net 25
press enter.

If the networking connection to your SMTP server is good, it should return a message like 220 .... If it returns Could not open connection to ..., that means the networking connection to SMTP server is bad, or outbound 25 port is blocked by anti-virus software, firewall or ISP. Please have a look at the following screenshot:

SMTP 25, 587, 465 port¶

25 port is the default SMTP server port to receive email. However, some ISP block outbound 25 port to prevent user to send email directly to other SMTP server. Therefore, many email providers also provide an alternative port 587 to receive email from such users. 465 port is the common port used to receive email over implicit SSL connection. If you use telnet to test 465 port, it doesn’t return the “220…”, because it requires SSL hand shake. But if the connection is ok, telnet returns a flash cursor.

“5xx … IP address block or on black list or bad reputation” Exception¶

This error means SMTP server blocks your IP address or email content. You can try to set user/password in your codes to do user authentication and try it again. If email client set user authentication, most SMTP servers do not check client source IP address in black list.

“5xx user authenticaton” Error¶

TThis error means user authentication is failed, you should check whether you input correct user/password. Password is always case-sensitive.

“5xx relay denied” Error¶

For anti-spam policy, most SMTP servers do not accept the email to outbound domain without user authentication. You should set user/password in the codes and try it again.

“5xx Must issue a STARTTLS command first”¶

This error means SMTP server requires SSL/TLS connection. You should enable SSL/TLS connection like this:

' If your smtp server requires TLS connection, please add this line
oSmtp.ConnectType = 1

“No supported authentication marshal found!”¶

This error means SMTP server doesn’t support user authentication or it requires user authentication over SSL/TLS connection. You can try to remove user/password in your codes and try it again.

Other error returned by SMTP server¶

If SMTP server returns an error, it usually returns description about this error. Some descriptions also include a HTTP link, you can go to this linked web page to learn more detail. You can also use the following codes to generate a log file to learn all SMTP session between client and server.

[VB 6.0 - Using log file to detect SMTP server response - Example]

oSmtp.LogFileName = "d:\smtp.txt"

Process Bounced Email (Non-Delivery Report)¶

If you sent email successfully without error, that means the email has been submitted to the SMTP server. The SMTP server will deliver the email in background, if the email couldn’t be delivered, a Failure Report (NDS) will be sent back to your sender email address.

To retrieve and parse Failure Report (NDS), you should monitor your sender mailbox. I recommend that you use EAGetMail to monitor your sender mailbox using POP3/IMAP4/Exchange WebDAV/Exchange Web Service protocol. After you installed EAGetMail on your machine, there are several full samples named “parse_report.*” for VB6, Delphi, Visual C++ in the installation path.

Email Tracking¶

Email tracking is used to verify that emails are actually read by recipients. There are two common solutions: Read Receipt and Linked Image Tracking

To learn more detail about Process Bounced Email (Non-Delivery Report) and Email Tracking, please have a look at this topic: Process Bounced Email (Non-Delivery Report) and Email Tracking

Bulk Email Sender Guidelines¶

If you are a mail listing provider and send bulk emails every day, of course you don’t want your emails are blocked or moved to Junk folder of the recipient mailbox.

To increase the inbox delivery rate of your messages, make sure that all recipients on your distribution lists actually want to receive the mail. Have a look the topic for some tips on how to make sure your messages are welcomed by most email providers:

Bulk Email Sender Guidelines

32bit/x64 ActiveX DLL¶

Seperate builds of run-time dll for 32 and x64 platform

File	Platform
Installation Path\Lib\native\x86\EASendMailObj.dll	32 bit
Installation Path\Lib\native\x64\EASendMailObj.dll	64 bit

Distribution¶

Standard EXE

For VB6, C++, Delphi or other standard exe application, you can distribute EASendMailObj.dll with your application to target machine without COM-registration and installer. To learn more detail, please have a look at Registration-free COM with Manifest File.
Script

For ASP, VBScript, VBA, MS SQL Stored Procedure, you need to install EASendMail on target machine by EASendMail installer, both 32bit/x64 DLL are installed and registered.

Next Section

In this section, I introduced how to send email in a simple VB6 project using SMTP protocol. At next section I will introduce how to send email over SSL/TLS connection in VB 6.0.

VBScript, JScript\Simple	Send a simple email from ASP Classic.
VBScript, JScript\SimpleQueue	Send email from ASP Classic to EASendMail Service.
VBScript\GmailOauth	Send email using Gmail OAUTH/XOAUTH2.
VBScript, JScript\AdvancedQueueWithDatabase	Send email from ASP Classic to EASendMail Service, background service will select recipients from database and write result back to database.

Simple	Send a simple email from Delphi 7.
HtmlMail	Send text/html email using Web Browser Control Editor
Mass	Send mass emails using thread pool.
Oauth	Send email using Gmail/Office365/Hotmail OAUTH/XOAUTH2.

Simple	Send a simple email from VB 6.0.
HtmlMail	Send text/html email using Web Browser Control Editor
Mass	Send mass emails using thread pool.
Oauth	Send email using Gmail/Office365/Hotmail OAUTH/XOAUTH2.

Simple	Send a simple email from VC++.
HtmlMail	Send text/html email using Web Browser Control Editor
Mass	Send mass emails using thread pool.
Oauth	Send email using Gmail/Office365/Hotmail OAUTH/XOAUTH2.

C#, VB, JScript\Simple	Send a simple email from ASP.NET form.
C#, VB, JScript\SimpleQueue	Send email from ASP.NET to EASendMail Service.
C#, VB\GmailOauth	Send email using Gmail OAUTH/XOAUTH2.
C#, VB, JScript\AdvancedQueueWithDatabase	Send email from ASP.NET to EASendMail Service, background service will select recipients from database and write result back to database.

Server	Port	SSL/TLS
smtp.gmail.com	25, 587	TLS
smtp.gmail.com	465	SSL

C#, VB\WebProject1\SimpleController	Send a simple email from ASP.NET MVC by Form Post/Ajax Post.
C#, VB\WebProject1\GmailOauthController	Send email using Gmail OAUTH/XOAUTH2.
C#, VB\WebProject1\MassController	Send mass emails using background thread pool.
C#, VB\WebProject1\DbRecipientsController	Send mass emails using background thread pool, select recipients from database and write result back to database.

C#, VB\Simple	Send a simple email from .NET Windows Form.
C#, VB\HtmlMail	Send text/html email using Web Browser Control Editor
C#, VB\Mass	Send mass emails using thread pool.
C#, VB\Oauth	Send email using Gmail/Office365/Hotmail OAUTH/XOAUTH2.

C#, VB\Simple	Send text/plain or html email from Microsoft Store App (UAP).
C#, VB\Mass	Send mass emails using thread pool from Microsoft Store App (UAP).
C#, VB\GmailOauth	Send email using Gmail OAUTH/XOAUTH2.

Tutorial Index

Send Email in VB 6.0 - Tutorial¶

Send email in a simple VB6 project using SMTP protocol¶

Installation¶

Add Reference¶

[VB 6.0 - Send email - Example]¶

Common SMTP Transport Error¶

TLS 1.2¶

Where can I get my SMTP email server address, user and password?¶

Email Address Syntax and Multiple Recipients¶

From, ReplyTo, Sender and Return-Path¶

Mail Priority¶

Troubleshooting¶

“No Such Host” Error¶

Common “Socket/Networking Connection” Error¶

Using Telnet to detect networking connection to SMTP server¶

SMTP 25, 587, 465 port¶

“5xx … IP address block or on black list or bad reputation” Exception¶

“5xx user authenticaton” Error¶

“5xx relay denied” Error¶

“5xx Must issue a STARTTLS command first”¶

“No supported authentication marshal found!”¶

Other error returned by SMTP server¶

Process Bounced Email (Non-Delivery Report)¶

Email Tracking¶

Bulk Email Sender Guidelines¶

32bit/x64 ActiveX DLL¶

Distribution¶

Send Email over SSL/TLS in VB 6.0¶

SSL and TLS Introduction¶

TLS 1.2¶

[VB 6.0 - Send Email over SSL/TLS Setting - Example]¶

[VB 6.0 - Send email over implicit SSL on 465 port - Example]¶

[VB 6.0 - Send email over TLS (Explicit SSL) on 25 or 587 port - Example]¶

SMTP Setting for Gmail, Yahoo, Hotmail and Office 365¶

Send Email using Gmail in VB 6.0¶

Introduction¶

Gmail App Password¶

[VB 6.0 - Send email using Gmail account over implicit SSL on 465 port - Example]¶

[VB 6.0 - Send email using Gmail account over explicit SSL (TLS) on 25 or 587 port]¶

Gmail SMTP OAUTH¶

TLS 1.2¶

Send Email using Yahoo in VB 6.0¶

Introduction¶

[VB 6.0 - Send email using Yahoo over Implicit SSL on 465 port - Example]¶

[VB 6.0 - Send Email using Yahoo over Explicit SSL (TLS) on 25 or 587 Port - Example]¶

TLS 1.2¶

Send Email using Hotmail/Live/Outlook/Office 365 in VB 6.0¶

Introduction¶

[VB 6.0 - Send Email using Hotmail/Live/Outlook over Explicit SSL (TLS) on 25 or 587 Port - Example]¶

Hotmail SMTP OAUTH¶

Send Email using Office 365¶

App Password and SmtpClientAuthenticationDisabled¶

[VB 6.0 - Send email using Office 365 over explicit SSL (TLS) on 587 port - Example]¶

Office365 SMTP/EWS/Ms Graph API OAUTH¶

Send Email directly without SMTP server(MX DNS lookup) in VB 6.0¶

Introduction¶

[VB 6.0 - Send email without specified SMTP server (MX record DNS lookup) - Example]¶

Send HTML Email in VB 6.0¶

Introduction¶

[VB 6.0 - Send HTML email - Example]¶

Import Html to email directly¶

Send Email with Attachment in VB 6.0¶

Introduction¶

[VB 6.0 - Add attachment from local disk or remote URL - Example]¶

Send Email with Embedded Images in VB 6.0¶

Introduction¶

[VB 6.0 - Send email with embedded images - Example]¶

[VB 6.0 - Send email with embedded images - ImportHtml - Example]¶

Send Email with Digital Signature in VB 6.0 - S/MIME with SHA1, SHA256 and SHA512¶

Introduction¶

[VB 6.0 - Send email with digital signature (S/MIME) - Example]¶

Signature Algorithm¶

Encrypt Email in VB 6.0 - S/MIME with RC2, 3DES and RSAES-OAEP¶

Introduction¶

[VB 6.0 - Email Encryption (S/MIME) - Example]¶

Encryption Algorithm¶

Send Email Asynchronously in VB 6.0¶

Introduction¶

[VB 6.0 - Send email with event handler in asynchronous mode - Example]¶