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In this chapter, the outputs or results of the project will be discussed by using an example. The screenshots of the entire mail system will be shown and the description of these screenshots also will be provided in this chapter. The users of the example here are Ying, the sender and Visnny, the receiver. Ying will first send a mail to Visnny and Visnny will reply a message to Ying as well as convert the scanned document by using the Optical Character Recognition (OCR) mechanism. Besides that, the discussion of the result and this project will be included here.
When Ying wants to send or read mail, she needs to connect to the mail server using the IP address of the mail server. For example, in the figure 5.1, the IP address of the mail server is 192.168.1.21, Ying needs to type https://192.168.1.21 in order to connect to the mail server. After successfully connecting, an interface of a webpage will be displayed. Ying needs to login by entering her username and corresponding password in the webpage to prove that she is the authenticated user before she can send or read mail.
Yingneeds to login using username and password
The IP address that use to connect to the mail server
Figure 5.1: Login interface for user
After Ying has login, the mailbox will be shown. Here, Ying can choose to do some actions such as compose a new mail, checks mail, deletes mail, or creates a new folder. Figure below shows the interface of the mail box.
Figure 5.2: Mailbox of user
When Ying chooses to compose a new mail, she needs to click on the "Compose" and an interface for Ying to write a mail will be displayed. The figure below shows that Ying wants to send to Visnny, who has the email address as email@example.com, without scanned document. The subject of the mail is "test send mail" while the content of the mail is "this is testing".
Content of the mail
Subject of the mail
Figure 5.3: Interface of compose mail
After writing the mail, Ying can send the mail by clicking the "send" button. The sent mail will be shown in the sent folder. The figure below shows that the mail was already sent to Visnny and was shown in sent folder.
Figure 5.4: The sent mail contain in sent folder
On the other side, Visnny also needs to login with username and password before she can read the mail which is sent by Ying. After logged in successfully, she will be able to see the mail in the inbox folder.
Figure 5.5: Mail sent from Ying
Visnny can read the mail by clicking on the mail. The content of the mail is show in Figure 5.6. Note that the email has been scanned for viruses and is safe to be read.
Safe to be read
Figure 5.6: The content of the mail
Now Visnny wants to reply a mail to Ying. She first scans her document and saves the scanned image into computer. She will need to know that content of the scanned image is correct or not. Hence, she will need to access the OCR mechanism, which is already implemented in the mail server. To access this mechanism, she must click "OCR Document" button. An interface for file upload will be shown. Visnny then finds the scanned image by using the file browsing features. After that, she will need to click "OK". A process will be started, where it will convert the scanned image into a text file. When the conversion process is completed, she can now edit the content of the scanned image. After editing, she copies the content as content of mail then send to Ying.
"OCR Document" button
Figure 5.7: Click the "OCR Document" button to open a new page for uploading scanned document
Click the "Browse" button
to choose scanned
document to upload
Figure 5.8: A new page to browse the scanned document
The scanned document
Figure 5.9: The uploaded scanned document
The wrong information
Content of the scanned document
Figure 5.10: Convert successfully
The information that Visnny needs to edit
Figure 5.11: Visnny edits the information
Figure 5.12: Visnny copy the content into text box
Now, the receiver is Ying and the subject is "Reply with OCR". Visnny clicks the "Send" button to send the mail to Ying. The figure below shows that the mail was sent successfully.
Figure 5.13: Mail sent to Ying successfully
The Figure 5.14 shows that Ying received the mail.
Figure 5.14: Ying received the mail
Figure 5.15: The content of the mail
In this project, Postfix had been selected as MTA for the mail server. There are also other MTAs which are popularly used by people such as Exim, qmail, and Sendmail. The current versions of each MTA have similar features. All of them have the following characteristics :
Afford to handle very large amounts of mail
Good security record
Source code is ready in a free manner
Communicate with many of the SMTP variants in use
Communicate with databases in many formats
The choice of MTA is very critical. A bad choice will be increased risk of security. For example, Sendmail runs as one big process with root privilege . Some of the tasks require root privilege thus monolithic Sendmail process runs with maximum privilege level. With this monolithic architecture, malicious user will use the root privilege to get control of the whole system. Besides that, decreased of reliability will be happened too. MTAs need to maintain the mailbox and mail queue. The mailbox and mail queue need to be updated. The reliability problem comes if multiple processes try to access these shared storage. A good MTA can remain well for years.
Postfix has a lot of main configuration files like Exim and Sendmail. It is table-driven, everything is a table which can be represented in all kinds of ways such as plain text files, databases, relational databases and more. Postfix offers excellent flexibility and ease of administration without affecting strict security goals. qmail also provides high security, but it does not give the administrator like Postfix in terms of flexibility due to design policy. The Sendmail team expressly admit the existence of Postfix as an influence on their next-generation replacement for Sendmail. Besides that, Postfix is more efficient than Exim but not easily seen on modern hardware degree even with very high load. It uses about the same amount of memory with qmail but qmail uses more bandwidth than Postfix due to deliberate design of qmail. The reason is qmail can only send a single message per SMTP session even there are multiple messages going through the same host. The Postfix community is very active and online documentation is quite good. Table below shows the comparison between these 4 MTA:
Table 5.1: MTA Comparison
If you areâ€¦
Worried about security
Wanting minimum hassle
MTA Suitability from 0 (bad) to 3 (good)
From the table above, Postfix has good documents and clear examples. As a beginner in setup a mail server, this is a great advantage for users to have a guide from these documents and examples. A guaranteed security is needed in mail system and Postfix is also secured and modern among these MTAs. qmail is secured too but it is very old and it does not support modern mail standards as well as IPv6. It is also not well-maintained since the author has not released updates or new version since 1997 and does not permit others to make releases. Besides that, Postfix also has minimum hassle which is more predictable. We do not require Postfix to run in Windows since the operating system that we use is CentOS.
In addition, there is no commercial mail servers that provide OCR function to users. To implement OCR function for users to convert scanned documents or hard copy of documents into text documents, Tesseract is selected as OCR mechanism in this project. Tesseract by default only supports tiff files. It does not support other image types such as jpeg, png, gif and others. To process and convert other image types, extra image processing software or tools need to be installed. Thus, Leptonica, an open source C library for image processing is needed in this project.
This chapter discusses the results and screenshots are provided. This chapter also includes the discussion about the result and the reason of choosing Postfix as MTA. The result of comparison show that Postfix is suitable to use in this project. Furthermore, this chapter also covers the importance of Leptonica in this project. Leptonica is used in processing other image formats instead of tiff format. The next chapter will be discussing the conclusion and future works of this project.