Open SMTP Server Without Authentication – Outgoing Mail SMTP Server – Five Simple Ways to Set it Up Right and Not to Become a Spammer

How many letters you send every day with your outgoing mail SMTP server? One hundred? Perhaps one thousand?

You use bulk mailing to communicate with your customers, to send newsletters and commercial proposals and it is an integral part of your business

In this case, sometimes you face “your-e-mail-can’t-be-delivered” problem. It is normal, when 5-10 messages out of a thousand can’t be delivered (of course if you have a clear, healthy and well maintained subscriber list).

Now what will happen, if 10-20% or even all of your messages never reach their destination? This nightmare may very well realize, if somebody classified you as a spammer.

Today almost 90% of all sent emails are spam. So, it is not surprising that everyone tries to avoid spam. Filters are trying to block as much mail as they can, providers create much severer anti-spam filters. Then your legitimate business correspondence is sometimes blocked.

You are very distressed when this happens. Let me try to help you make anti-spam filters your friend and help you configure your own outgoing mail SMTP server. After that anti-spam filters will recognize your mail from afar and treat them as old friends.

First of all, let’s take a look at the diagram below. It describes the basic steps, which your message makes when you are emailing.

Of course I am presuming you have a healthy, totally legal opt-in list and your message does not classify as spam. If not, these rules will not help you that much.

To achieve this we need to observe five simple rules. These rules were invented to check your messages before they are delivered to recipient’s mailbox. Anti-spam filters are built on “assigning trust”. If something looks suspicious, they will decrease your trust score and if it is decreased enough, your letter will sink into oblivion forever.

Here is what you have to do when you start your own outgoing mail SMTP server, or when you are going to do bulk mailing:

* Get your own Static IP address

* Configure forward & reverse DNS resolution

* Check black – lists

* Configure SPF

* Configure Domain Keys (optional)

May be these items seem a little bit alien to you, but in fact, they are quite simple and now we are going to analyze them.

Get your own static IP

Most, if not all of your regular Internet providers will not give this to you by default. You are usually assigned with a floating (dynamic) IP address and this IP changes every time you connect to the Internet. This is like shooting a moving target and most email servers will block you if your connection comes from such a dynamic IP. So first priority of the day for you would be to call your provider and get a static IP from them.

Forward & Reverse DNS resolution

Another mandatory rule for your local outgoing mail SMTP server – you must take care of is configuring forward & reverse DNS resolution. DNS resolution occurs when a client queries a name server to obtain the IP address with which it wants to establish a connection. If a name server in the local domain cannot resolve a client’s request, it queries parent servers to locate a server that can.

They can create a form of authentication, that shows a valid relationship between the owner of a domain name and the owner of an IP address that belongs to the email SMTP server. This validation add a lot to your trust score.

It is just an additional way to find you by your domain name if you go bad and start spamming. Usually spammers and phishers can’t pass through this because they do not want to show their real name to anybody – they like to use stolen or hijacked domains and IP addresses. No provider will agree to register a domain without some form of ID (like credit card).

Forward & reverse DNS resolutions proceeds with the help of so-called A and PTR-records. Don’t forget to add these records in your DNS – they are used for implementing DNS look ups. Also they will help your openly work on the Internet. You can ask your provider or domain registrar to do this. Therefore, you will be more trusted with spam filters and different servers.

Please note, that if you set an “A record” of your domain name in your DNS, this does not mean that your Internet provider configured the PTR record automatically. At least make sure you check it with them because sometimes they add this and sometimes they don’t.

Black – list

DNS blacklists (or DNS block-lists) are accessed with the use of DNS query. Thay are the lists of IP addresses that are stored in remote database. They are used to block IP addresses that are sending spam. Mail server will check the existence of IP-address of the client, from which it receives the message and after the positive response the message is detected as spam will be blocked.

When you find out the reason of failure you can check it with blacklist site. Or you can use the manual directions of removing your IP from the list (most of the sites contains them)


SPF is not a “sun protection factor”, as you might think. SPF is the next useful, but optional DNS record. It shows hosts that have rights to send emails for a specific domain. SPF helps to verify whether source IP of the sender is permitted to transfer messages for this domain. The server may reject your email or tag it as spam, if you are sending an email from the IP that is different from the specified.

SPF record will help you to show your good intentions to the receiving servers. If you want to use this type of DNS record you can visit the site, which knows everything about SPF – Then ask your domain registrar to help you to setup SPF. Some of them have special wizards in their configuration panel. They can help you to setup your SPF automatically.

Domain Keys (optional)

There is additional inspection standard, that is not used as widely. It is matter of argument if it will help or not. That’s because only a few providers do check it.

Domain Keys was created to identify the sender of emails. It added cryptography to ensure that only a person with the right key can send a certain email and it is very similar to SPF.

Domain Keys does not filter spam itself, as you can see, but if you show a correct domain, filtering mechanisms can work more effectively. So they will not mark you as spammer.

We came to an end. Now you can see that paying attention to such trifles helps you to act as openly as it is humanly possible.

This is especially useful when you are going to create your own outgoing mail SMTP server, it will help you avoid trouble with the spam filters – they trust senders who specified most complete and visible data.

These five rules are not so difficult as they seem, and following them might be quite easy and very rewarding indeed.

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