Adding Mailing Capability to your KMS

In the previous part of this series (Adding an Address Book to your KMS, p110,

July 06) we added address book and contact management capabilities to our KMS system. We're back

after a month's gap and this month, we make use of that data to send our

contacts e-mail, either on-demand or on a pre-configured schedule. This way, we

can send them specific contact messages or pre-created alerts and newsletters for various purposes. And what's

more, since we're using an SQL Server database for our backend, we simply add

all the messages we send (and all the replies we receive) intothis database for

automatic database-based archival.

Unlike our address book, DMS and other modules so far, this module requires a

few components to be installed on our application server before it gets

cracking. Namely, we would need an SMTP and a POP3 server. If you want to use

Newsgroup functionality though the KMS (not a part of the project at this

point), you need to install an NNTP server as well. Since we're anyway using a

Windows Server 2003 system for our app server, this is already there with the OS

and all you need to do is go into Add/Remove Programs> Add/Remove Windows

Components and install the SMTP, POP3 and NNTP servers from there.

Alternatively, you can launch the Manage Your Server front-end from the

Administrative Tools menu and audit from there.

Sending mail



Sending out mail using ASP.NET requires just a couple of lines of code. All

you do need to do is set up your recipient list, add any attachments you have, include the subject and body of

the e-mail and call the Send function. If additionally, the mail server administrator configured your SMTP server to

require authentication before sending out mail (this helps prevent someone/thing

from using your SMTP server as a spam relay and is really recommended), you need

an additional couple of lines that specify the username and password to the SMTP

backend in .NET. You should import the System.Web.Mail namespace for this module

to work.

Public Sub AddAttachment(ByVal FullPathToFileOnServer As String)



Dim MA As MailAttachment, L As Int32


MA = New MailAttachment(AttFilePath)


If (m_Attach Is Nothing) Then


        ReDim m_Attach(0)


        L = 0


Else


        L = m_Attach.Length


        ReDim Preserve m_Attach(L - 1)


        L -= 1


End If


m_Attach(L) = MA


End Sub

Our SMTP and POP modules use a common Attachment Handler to save attachments into our DMS. This maintains quality of data in our DMS database and avoids duplicity

Do note that to add attachments in .NET, you need to add it to the

Attachments collection as in the above code. m_Attach is an object of type

System.Web.Mail.MailAttachment. Next, we compose our SMTP mail message and send

it out.

Public Sub SendMail()



Dim Msg As MailMessage, MA As MailAttachment


    Try


    Msg = New MailMessage


    With Msg


        ' Set username & password


        ' if authentication is required


        ' setup: BodyFormat, From,


        ' To, Cc/Bcc, Subject and Body


        ' properties of the Msg object

If ((Not m_Attach Is Nothing) AndAlso (m_Attach.Length > 0)) Then



    For Each MA In m_Attach


        .Attachments.Add(MA)


    Next


    End If


End With


SmtpMail.SmtpServer = SmtpServer


SmtpMail.Send(Msg)


Catch Ex As Exception


        ' error handler


    End Try


End Sub

Saving to database


Before the e-mail is actually sent out, it is best to store our entire message
into our SQL Server database. Our table structure mimics the SMTP construct for

convenience with attachments stored as objects in the DMS table we created in

part 1 of the series (Roll your own IPMS, p66, June 2006). The code to do all

this is in our DMS module, we simply call the function as follows:

SaveDMSAsset( AttachmentFilename, MailFromUserID, MailSubject, MailFromUserID

)

SaveDMSContent ( MailFromUserID, MailBodyContent )

AttachmentFilename is the name of the attachment file we are adding to the

DMS. The MailFromUserID is the ID of the person sending this mail. We are



ignoring a lot of other fields in the DMS table (like document ID and so on) as
they will be automatically generated by the SaveDMSAsset function.

MailBodyContent used in the second function is the body of the mail being sent

out. SaveDMSContent directly stores data into a DMS table called DMS_TextContent

(fields being a unique ID, and a Text datatype Content).



Of course, it will be ridiculous to store duplicates of the document in the DMS
table. But, that is taken care of by the DMS code that we call, which first

checks the table to see if the document is already in there and stores the one

we specify only if it is not already present.

Receiving e-mail


This is slightly complicated. .NET does not provide the means to talk to the
POP3 server the same way as the SMTP server and we need to actually write our

own POP3 client to log on to the server using Socket connections and retrieve

messages. The code for this client is quite large to be given in this article in

any useful size and context. It suffices to say that we shall simply call the

below sequence to do our job:

Dim Msg As POPMessage



...


Msg = RetrievePOPMessage()


If (Not Msg Is Nothing) Then


    CheckSpam( Msg )


    SaveDMSContent( Msg.Body )


    For Each m_Attach In _


        Msg.Attachments


    SaveDMSAsset( m_Attach, _


        MailToUserID, _


        Msg.Subject, MailToUserID )


    Next


End If

Finally, we store this content into our database, using the same function (SaveDMSAsset)

as above.

We now have just one final part next month where we create a portal that links

all our various modules together. This would let all your users access the

system from one consistent interface. The final completed application would be

carried in our October 2006 Enterprise disk, along with a full installer program that will install, configure and walk you through the initial working of

the application.