Download/Retrieve Email from Gmail account in VB.NET

In previous section, I introduced how to retrieve email over SSL connection. In this section, I will introduce how to download email from your Gmail account in VB.NET.

Introduction

Gmail POP3 server address is pop.gmail.com. It requires SSL connection on 995 port, and you should use your Gmail email address as the user name for user authentication.

Gmail IMAP4 server address is imap.gmail.com. It requires SSL connection on 993 port, and you should use your Gmail email address as the user name for user authentication. For example: your email is gmailid@gmail.com, and then the user name should be gmailid@gmail.com.

To retrieve email from Gmail account, you need to enable POP3 or IMAP4 access in your gmail account settings.

Because Gmail POP3 server doesn’t work like normal POP3 server, it hides old emails automatically even the email was not deleted, so we suggest that you use IMAP4 protocol.

Server Port SSL Protocol
pop.gmail.com 995 SSL required Pop3
imap.gmail.com 993 SSL required Imap4 (recommended)

Important

If you got authentication error, you need to enable Allowing less secure apps or Sign in using App Passwords.

Another way is Gmail OAUH, please see Gmail IMAP OAUTH section.

Note

Remarks: All of examples in this section are based on first section: A simple VB.NET project. To compile and run the following example codes successfully, please click here to learn how to create the test project and add reference to your project.

[VB.NET Example - Retrieve email from Gmail account]

The following example codes demonstrate how to download email from Gmail account using IMAP4 protocol.

Because Gmail POP3 server doesn’t work like normal POP3 server, it hides old emails automatically even the email was not deleted, so we suggest that you use IMAP4 protocol.

Note

To get the full sample projects, please refer to Samples section.

Imports System.Globalization
Imports System.Text
Imports System.IO
Imports EAGetMail 'imports EAGetMail namespace

Module Module1

    Function _generateFileName(ByVal sequence As Integer) As String
        Dim currentDateTime As DateTime = DateTime.Now
        Return String.Format("{0}-{1:000}-{2:000}.eml",
                            currentDateTime.ToString("yyyyMMddHHmmss", New CultureInfo("en-US")),
                            currentDateTime.Millisecond,
                            sequence)
    End Function

    Sub Main()

        Try
            ' Create a folder named "inbox" under current directory
            ' to save the email retrieved.
            Dim localInbox As String = String.Format("{0}\inbox", Directory.GetCurrentDirectory())

            ' If the folder is not existed, create it.
            If Not Directory.Exists(localInbox) Then
                Directory.CreateDirectory(localInbox)
            End If

            ' Gmail IMAP server is "imap.gmail.com"
            Dim oServer As New MailServer("imap.gmail.com",
                    "gmailid@gmail.com",
                    "yourpassword",
                    ServerProtocol.Imap4)

            ' Enable SSL/TLS connection, most modern email server require SSL/TLS connection by default.
            oServer.SSLConnection = True
            ' Set 993 IMAP SSL Port
            oServer.Port = 993

            Console.WriteLine("Connecting server ...")

            Dim oClient As New MailClient("TryIt")
            oClient.Connect(oServer)

            Dim infos As MailInfo() = oClient.GetMailInfos()
            Console.WriteLine("Total {0} email(s)", infos.Length)

            For i As Integer = 0 To infos.Length - 1
                Dim info As MailInfo = infos(i)
                Console.WriteLine("Index: {0}; Size: {1}; UIDL: {2}",
                        info.Index, info.Size, info.UIDL)

                ' Retrieve email from IMAP server
                Dim oMail As Mail = oClient.GetMail(info)

                Console.WriteLine("From: {0}", oMail.From.ToString())
                Console.WriteLine("Subject: {0}" & vbCr & vbLf, oMail.Subject)

                ' Generate an unqiue email file name based on date time.
                Dim fileName As String = _generateFileName(i + 1)
                Dim fullPath As String = String.Format("{0}\{1}", localInbox, fileName)

                ' Save email to local disk
                oMail.SaveAs(fullPath, True)

                ' Mark email as deleted from IMAP server.
                oClient.Delete(info)

            Next

            ' Quit and expunge emails marked as deleted from IMAP server.
            oClient.Quit()
            Console.WriteLine("Completed!")

        Catch ep As Exception
            Console.WriteLine(ep.Message)
        End Try

    End Sub
End Module

Gmail IMAP OAUTH

By default, you need to enable “Allowing less secure apps” in Gmail/G Suite, then you can retrieve email with user/password IMAP4 authentication.

However Google will disable traditional user authentication in the future, switching to Google OAuth is strongly recommended now.

Or you can generate App Passwords and use this app password instead of your user password.

[VB.NET Example - Retrieve unread/new email from Gmail account]

Because IMAP/EWS/WebDAV support read mail flag, with this feature, we can also retrieve unread/new email only from Gmail like this

Imports System.Globalization
Imports System.Text
Imports System.IO
Imports EAGetMail 'imports EAGetMail namespace

Module Module1

    Function _generateFileName(ByVal sequence As Integer) As String
        Dim currentDateTime As DateTime = DateTime.Now
        Return String.Format("{0}-{1:000}-{2:000}.eml",
                            currentDateTime.ToString("yyyyMMddHHmmss", New CultureInfo("en-US")),
                            currentDateTime.Millisecond,
                            sequence)
    End Function

    Sub Main()

        Try
            ' Create a folder named "inbox" under current directory
            ' to save the email retrieved.
            Dim localInbox As String = String.Format("{0}\inbox", Directory.GetCurrentDirectory())

            ' If the folder is not existed, create it.
            If Not Directory.Exists(localInbox) Then
                Directory.CreateDirectory(localInbox)
            End If

            ' Gmail IMAP server is "imap.gmail.com"
            Dim oServer As New MailServer("imap.gmail.com",
                    "gmailid@gmail.com",
                    "yourpassword",
                    ServerProtocol.Imap4)

            ' Enable SSL/TLS connection, most modern email server require SSL/TLS connection by default.
            oServer.SSLConnection = True
            ' Set 993 IMAP SSL Port
            oServer.Port = 993

            Console.WriteLine("Connecting server ...")

            Dim oClient As New MailClient("TryIt")
            oClient.Connect(oServer)

            ' retrieve unread/new email only
            oClient.GetMailInfosParam.Reset()
            oClient.GetMailInfosParam.GetMailInfosOptions = GetMailInfosOptionType.NewOnly

            Dim infos As MailInfo() = oClient.GetMailInfos()
            Console.WriteLine("Total {0} unread email(s)", infos.Length)

            For i As Integer = 0 To infos.Length - 1
                Dim info As MailInfo = infos(i)
                Console.WriteLine("Index: {0}; Size: {1}; UIDL: {2}",
                        info.Index, info.Size, info.UIDL)

                ' Retrieve email from IMAP server
                Dim oMail As Mail = oClient.GetMail(info)

                Console.WriteLine("From: {0}", oMail.From.ToString())
                Console.WriteLine("Subject: {0}" & vbCr & vbLf, oMail.Subject)

                ' Generate an unqiue email file name based on date time.
                Dim fileName As String = _generateFileName(i + 1)
                Dim fullPath As String = String.Format("{0}\{1}", localInbox, fileName)

                ' Save email to local disk
                oMail.SaveAs(fullPath, True)

                 ' mark unread email as read, next time this email won't be retrieved again
                If Not info.Read Then
                    oClient.MarkAsRead(info, True)
                End If

                ' if you don't want to leave a copy on server, please use
                ' oClient.Delete(info)
                ' instead of MarkAsRead

            Next

            ' Quit and expunge emails marked as deleted from IMAP server.
            oClient.Quit()
            Console.WriteLine("Completed!")

        Catch ep As Exception
            Console.WriteLine(ep.Message)
        End Try

    End Sub
End Module

TLS 1.2

TLS is the successor of SSL, more and more Email 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

Next Section

At next section I will introduce how to download emails from Yahoo account.

Appendix

Comments

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