My virtual lab

This article has two purposes. It is the second part of the Mikrotik IPSec series and, at the same time, a short virtualization guide. I will present how we can simulate most common scenarios them in virtual environment.

Although I am using Oracle VirtualBox (referred to as VBox from here on out) for these demonstrations, you can use any other virtualization solution in a very similar way. We don’t need any special features of the virtualization solution. You should only optimize your VMs based on the settings related to your environment. You can find my guides about VBox environment here and here.

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How to check the version of the update pack of the Microsoft Exchange Server 2013?

A few weeks ago it happens very unusual error with the e-mails received by the Microsoft Exchange Server 2013. All e-mails received from one specific e-mail address, which belongs to one of our vendors, are completely garbled.

Every e-mail is composed of several parts and contains the XML code. One day, suddenly, all e-mails are converted to plain text and the attachments are missing. When this anomaly appears, it affected all users.


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Manual test for the POP3 connection

This post will explain the procedure for manual testing of the e-mail receiving process. This procedure is useful for system administrators or programmers to narrow down problems in an operation of their e-mail server.

We can reproduce entire POP3 e-mail exchange process with manual typing of all commands. We can use this procedure when we need to test proper work between an e-mail server and an e-mail client.

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How to manually send the e-mail

This post will explain procedure for manual testing of the e-mail sending process. When you’re in doubt does your e-mail server works correctly, you can follow this procedure and check functionality.

We can manually simulate the client-server connection with the e-mail server whenever we need to test a connection or troubleshoot an errors in the communication.

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SMTP service status messages

A SMTP service is a part of the e-mail server responsible to receiving and delivering for an e-mail messages. It communicating with an e-mail client about every action. We, as end-users, can see some of this messages.

The SMTP server and a client doesn’t need whole test. There fore, a SMTP server can just return numerical code for it’s action. In courtesy to the user, SMTP server will return also text message in every e-mail sent back.

You can see from time to time that some e-mail stuck in outgoing queue or that it can’t be delivered to recipient. Such e-mail is short and usually have some text like You e-mail sent to the some_user can not be delivered because of and then some number and short explanation.

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