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Introduction
As we all know Yahoo has stopped POP3 access to its free email service. This article will explain you how to check HTTP based email account from a Visual Basic Application. This article is just a head-start to developing a framework for a full-fledged application which can be customized for similar HTTP based email accounts. Being it HTTP your program is guaranteed to work regardless of the type of internet connection you have.
The Concept and method
The concept is fairly simple. Something that we do all the time, but never think of achieving in the manner I am about to show. How do all of us check our Yahoo! Accounts? These are the steps we follow:
- Connect to the mail.yahoo.com website.
- Key in our login and password.
- Hit the �login� button.
After which, the traditional Yahoo! Mailbox page shows up.
Now let us try doing the same programmatically:
- Load the mail.yahoo.com website in one of our nested Internet Explorer Controls.
- Set the Login name and Password fields to our login/password combination.
- Invoke the �Submit� method of the form.
Simple! Isn�t it? Now, after following the above steps, the browser automatically loads up the Yahoo! Mailbox page. All that we have to do now is parse the HTML page correctly and extract the required information.
The YahooMailChecker Application
Let us call our application the YahooMailChecker Application. This is going to be a standard Windows Application (EXE) Project in Microsoft Visual Basic 6.0.
Our application will require the following references:
- Microsoft HTML Object library.
- Microsoft Internet Explorer.
Our applications will host the following controls:
- Timer control
- Status bar control.
We will require the timer control because we will be checking our Yahoo! Account at a periodic interval. And obviously the status bar will keep telling us what exactly the Internet Explorer is up to.
Connecting to the Yahoo! Mail site
As you must have guessed by now, the entire code will go inside the Timer controls, Timer event. I have set the interval of the timer control to 15 seconds, you will have to adjust this interval based on the speed of the internet connection you have.
Here is how our application will work:
- Create an instance of the Internet Explorer object and set it to our global variable.
- Start work inside the Timer controls event.
The Internet Explorer Object which we will use has an event called DocumentComplete, we will be using this event to get notified of the browser�s completion status. Inside this event, we will check if we have already being authenticated on the yahoo mail site or not. If yes, go ahead and extract the required information. If not, try logging in.
In order to connect to the Yahoo! Mail site you will be using the Navigate method of the Internet Explorer object.
Here�s the code snippet from the Timer control�s Timer event:
Private Sub tmrWorkerThread_Timer()
Dim FirstPart As String
Dim OpenBracket As Integer
Dim CloseBracket As Integer
Dim Actual As String
tmrWorkerThread.Enabled = False
sbYMC.Panels(1).Text = "Navigating"
YahooMail.navigate "http://mail.yahoo.com"
Do While YahooMail.readyState <> READYSTATE_COMPLETE
DoEvents
sbYMC.Panels(1).Text = YahooMail.StatusText
Loop
If InStr(YahooMail.document.body.innerHTML, "You must sign in to read or send mail") <> 0 Or InStr(YahooMail.document.body.innerHTML, "Invalid Password") <> 0 Then
With YahooMail.document
.All.Item("login").Value = "myloginid"
.All.Item("passwd").Value = "mypassword"
.Forms(0).submit
End With
Do While YahooMail.readyState <> READYSTATE_COMPLETE
DoEvents
sbYMC.Panels(1).Text = YahooMail.StatusText
Loop
Else
lblMailBoxState = "Authenticated"
End If
tmrWorkerThread.Enabled = True
End Sub
Let us try and understand the above code now. The above code works in the following manner:
- Navigate to the mail.yahoo.com site by calling the Navigate method of the Internet Explorer object. I have called my Internet Explorer �YahooMail�.
- Wait till the page loading is complete. This is achieved by waiting for the Browser�s completion status (READYSTATE_COMPLETE).
- Once the page is loaded check the HTML content to see if you have already logged in using some different session i.d. (yahoo maintains this in the form of cookies on the client�s machine). This check is made by checking for the �You must sign in to read or send mail� text inside the HTML content (InnerHTML). If this text is not found that means the browser is using an existing cookie (which had worked in the past).
That�s it!
The DocumentComplete event
Now that the page has loaded in our browser object, we need to extract the relevant information. This is done inside the DocumentComplete event of the Internet Explorer object.
Here is how the code inside this event looks like:
Private Sub YahooMail_DocumentComplete(ByVal pDisp As Object, URL As Variant)
If InStr(YahooMail.document.body.innerHTML, ">Inbox") > 0 Then
FirstPart = Mid(YahooMail.document.body.innerHTML, InStr(YahooMail.document.body.innerHTML, ">Inbox"), 20)
OpenBracket = InStr(FirstPart, "(")
CloseBracket = InStr(FirstPart, ")")
If OpenBracket = 0 Or CloseBracket = 0 Then
lblInboxCount = "No Unread Mails"
Else
Actual = Mid(FirstPart, OpenBracket + 1, CloseBracket - OpenBracket - 1)
lblInboxCount = Actual
End If
FirstPart = Mid(YahooMail.document.body.innerHTML, InStr(YahooMail.document.body.innerHTML, ">Bulk"), 20)
OpenBracket = InStr(FirstPart, "(")
CloseBracket = InStr(FirstPart, ")")
If OpenBracket = 0 Or CloseBracket = 0 Then
lblInboxCount = "No Unread Bulk Mails"
Else
Actual = Mid(FirstPart, OpenBracket + 1, CloseBracket - OpenBracket - 1)
lblBulkCount = Actual
End If
End If
End Sub
Let us now understand how this code works:
- If the target document contains the following text : �>Inbox� it means that you have logged into the account.
- Go ahead and hunt for the location of the above text.
- Extract the Unread mail count and then repeat the steps for the Bulk Mail folder.
Simple wasn�t it? That�s how simple it is! We just think all these things are complicated and miss out the real fun.
