What are SMTP Mail Relay Services?
How to get around your ISP blocking your ability to use any SMTP server other than theirs

By: Bruce Bahlmann - Contributing Author (your feedback is important to us!)

Created: May 26, 2005

Do you own a domain but can’t send email from it from your home computer? Perhaps you own a virtual company that hosts multiple email accounts however the broadband connection you maintain in your home office does not allow you to send emails from your purchased domain so as a result, any email you send from home must come from your home email account. In this article we will explain what you are experiencing as well as what your options are to correct it. 

Why can’t I send email from my domain? 

Simple Mail Transport Protocol (SMTP) is the mechanism that your email program uses to communicate with a mail server that is responsible for sending email to its recipients out on the Internet. The problem with SMTP is that prior to the outbreak of electronic junk mail (spam) is that SMTP had numerous security holes that would allow anyone to send email to anyone. Internet Service Providers (ISP) who provide email to their customers and as a result maintain their own SMTP server found they were inundated with spam. To combat spam, ISPs began blocking in-bound (from the Internet) SMTP traffic (port 25) which prevented non-customers from using their SMTP server for spam. However, ISP’s customers could send SMTP without authenticating and as it turned out, the anticipated reduction in spam didn’t really materialize. The latest SMTP changes have nearly put the lid on spam proliferation from an ISP’s perspective. These changes require their customers to authenticate with SMTP using their username (their email address), password, and some kind security encryption in order to send email which ensures the email sender’s true Internet Protocol (IP) address is captured in the process and the sending email address is the same address that is authenticated and has the correct domain of the ISP. In this way, ISP customers can no longer forge (spoof) their IP address or their “from” address. This way, anyone who wants to spam must use their real email address to do so which no one wanting to send large amounts of spam will venture to do. If all ISPs could be so bold as to do this, spam by and large would disappear.  

While all this added SMTP security works great to eliminate spam, it prevents anyone who owns a domain outside of the ISP’s network confines to interact with the services they have subscribed. For example, if an ISP customer has purchased a web hosting service which includes unlimited email accounts under that purchased domain, the customer will only be able to download the email as currently that portion of email services is not restricted by ISPs. However, in light of all the problems with spam, no SMTP traffic is permitted outside the ISPs network – nor is it permitted to enter the ISP’s network.  

Just when you think the ISPs have finally figured out a way to force their customers to use the email they were provided as part of their Internet service, the Internet community has proven once again that when faced with a problem of making money it will always innovate around the obstacle – enter the SMTP mail relay. The SMTP mail relay (also called "mail relay outbound", "mailhop outbound", "SMTP Relay Service", to name a few) is an ingenious answer to the newly added security implemented by ISPs to combat spam. The SMTP relay works like this: 

Customer email client attempts to send email

[SMTP: port 25] ---- > ISP (blocks outbound port 25)
RESULT: Failed sending of email to non-ISP hosted domain 

Customer email client attempts to send email

[SMTP: port 2525] --- > ISP (ignores) --- > SMTP relay --- > desired domain SMTP
RESULT: Success! Thanks to SMTP relay which redirects properly authenticated SMTP requests on port 2525 and send them on to port 25 on your requested domain 

There are a number of SMTP relay companies providing this service for a nominal fee. A list of these companies is provided below (service providers wanting to add their relay services to this list should contact Birds-Eye.Net):

Table 1.0 SMTP Relay Services

Notes in Above Table:
* - Counts double towards limited number of messages per plan

Essentially, for a $15 to $20 a year, one can send and receive email from a custom domain from anywhere (from your ISP, hotel, public wireless Internet, etc.). It is only a matter of time before web hosting companies take the hint and build their own SMTP relay services and offer that to their customers. If they don't the email services they offer as part of their hosting service for small businesses is going to look pretty pathetic. The plans above that have been highlighted in YELLOW, are the best buys for the money. However all plans still have undesirable things about them. For example AuthSMTP counts the SSL emails double for each one sent (this is a mere inconvenience as other SMTP mail relay/reflector services charge you extra for SSL). DynDNS has a great package for nearly the same price however SSL costs you even more money and there is a cap on daily email traffic. The best limitation if there has to be one is a monthly limitation because it will generally allow you to send lots of emails in one go. For example, if you do use a bulk mailer, you can send out 700 emails in one day just one time a month and still only pay for the equivalent of an economy service. Best advice is to just say no to daily email limitations.

One important thing to note when selecting an SMTP relay service is that most do not support bulk mailers. So, if you regularly use a bulk mailer for your business, you may have to do without that service until these SMTP mail relay services figure out how to support legitimate bulk mailing. You should also check to see if your prospective SMTP relay service supports individual accounts quotas. Quotas allow the master account to manage what percentage or how many emails can be sent per day or per per month so that no one account can use up the entire allotment of outbound emails allowed.

Also, not that there are other companies that offer SMTP relays or SMTP reflectors but if you read the fine print, they require you to maintain your email accounts with them. In other words, they do not provide a PURE SMTP mail relay. Stay away from these as the last thing you need is multiple email accounts. All you should ever need is one email account. If anyone tells you different, they are probably trying to sell you something you don't need.

Feedback received on article:

Birds-Eye.Net

Just wanted to say thanks for posting this information about the subject on "What are SMTP Mail Relay Services".

I was having trouble sending out email for the longest time before I found out the my ISP had blocked port 25. When I contacted them about this matter to allow me to send through the port again or make my account SSL login type, they said in the short version "to bad" we don't offer it and if you are not directly on the service you must use web mail. My ISP is charter.net. it's too bad when you are paying for a service, and then they turn something off to block you from using the service to the fullest and not let you know about it.

My profession calls for me to travel local and abroad and before this happened all was well in my world of e-mail. The reason I have not change it is because I have had it for so long and all of my business contacts have it. Well anyway thanks for the information and other companies need to post their information of services, to make it a little more competitive for the consumer. Oh and by the way you are my first sent e-mail, using the server from www.dyndns.com, the outbound service to see if it worked ;o)

Scott Litteral
President
FSL Enterprises, LLC.

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