Test SMTP Server

This article is a simple overview of testing via telnet into the SMPT server and the various services that are available to you online.

What SMTP Is:

SMTP stands for simple mail protocol and is the method behind email workflow on the Internet.  Have you ever wondered how emails get from the sender to the receiver?  It’s taking something similar to the process of delivering an actual letter. The SMTP service is a mail carrier on the Internet.  Message are directly sent to this server which sends mail on to the receiver.  It’s the Internet’s answer to the U.S. Postal Service.

Telnetting is an application layer protocol used on the Internet to provide bi-directional interactive test-oriented communication using a virtual terminal connection.

What Is Telnet?

It’s a network protocol that allows a user to be on one computer to log onto another computer that is a part of the same network.

What can be tested via Telnet into the SMPT Server?

• Find out whether a server is working
• Whether a firewall is blocking communication
• Does the mail server allow for transmitting of a domain or email address?
• The SMTP commands a mail server supports.
• The time it takes for a server to respond.
• Is the server responding with the right hostname?

Overview of Manual SMTP Testing:

As a telnet client, you must be verified for installation on the server.  Once done, you should find a mail server to sign into.  You will need the DNS MX record for a particular domain to proceed. To use the IP, you need the DNS PTR so start with the IP address that the Internet recognizes you have.

Data: Before starting the body of your message you should run the DATA command.  This command will explain all the other content.

Some mail servers support Pipelining.  That means the SMTP will wait until the DATA command is sent before responding to other commands  So, enter the MAIL FROM, RCPT TO, DATA commands before waiting for a response. At the beginning, define the address of the SMTP server.  Use a ns lookup command or another online service. The SMTP check service will include several stages as following: checking your server DNS Black List status, verifying MX Records, relaying configurations, PTR Record, verifying the email address.

 

Here are some online services that can help you test SMTP server:

MX Toolbox

This is a free service that performs simple tests such as SMTP Valid Hostname, SMTP Banner Check, SMTP TLS, SMTP Connection Time, etc.You are not allowed to define the port, enter a password, etc.  The number of tests is also limited.

Wormly:

Wormly offers a free trial to check your SMTP servers but will not allow defining the port or password; a secure connection is not available either. SMTP is a convenient solution that allows defining the port, gives the user a secure connection and authorization.  You can fill out both sender and recipient forms.

SMTPer:

SMTPer is a very convenient solution that that will let you define the port, provide the user with a secure connection and authorization.  You can fill out both sender and recipient forms.

Testsmtp:

You can check SMTP for certain parts of a process but does not provide a proper examination.  It does not provide a secure connection.