Stockholm, 4th November 2002


To whom it may concern,


Telia is one of the biggest ISP in Sweden. ISP means Internet service provider - somebody provides services and there are customers that purchase/use these services. It is a healthy economical symbiosis, if both customers are satisfied and ISP makes profit during operation. Customers should respect provider conditions (and have to pay for the service) from other side ISP should respect the customer and inform customers about important changes that affect service quality and price.

Telia, as a company that cares about the customers (and probably shareholders) sends out five months earlier a note, if raises prices with 25kr. What I, as customer, do appreciate this approach. is a non commercial, educative effort for popularization of operating systems and Internet services, offering shell accounts and other internet services as web space, mail etc. on all available systems. Today it offers nine operating systems (Linux/RedHat, Linux/Debian, FreeBSD, OpenBSD, NetBSD, OpenVMS/Alpha, OpenVMS/VAX, Solaris and Ultrix) and has about 30.000 users that are more or less proud that they are members of such free and open community that open horizons without making profit from it.

I know that it is hard to believe, but runs happily with broadband that Telia ADSL provides (0.5Mbps). It was enough and contract that Telia offered for ADSL users (Allmäna vilkor för teleabonnemang – 1 augusti 1994) did not mention any constraints regarding service usage giving enough space for hobby activities as    


If, Telia would follow this brave line regarding service quality and customer care, we will never come to this disastrous situation, when 30.000 users have lost their mail accounts.


It has been closed incoming SMTP port (25) for whole Telia home internet network, including Com Hem (cable modem) and of course ADSL network.


Polarhome, during this 3 years existence had hard times, and I already have a possible solution for “closed 25 port” problem, but is this a right approach? It should not be cat and mouse game. I pay for services and require from provider to deliver it. If provider has a problem with service delivery and plans to change the service quality, customers should be first who will be informed about changes, eventually it should be offered some product packet that provides same services.


I talked three times to customer support until somebody could answer the question, what really happened – actually officially confirmed my diagnose… and so far I have not got any other product offer that could provide about the same services that I had earlier.


Let analyze the reason, why Telia closed SMTP port (25) for incoming traffic.

·        Bandwidth problem – NO. If there will be problem with bandwidth Telia would close ftp port (21) or some of well know ports for PtP file sharing as Kazaa, fileshare etc.

·        Is it because of spam that originates from Telia network? – NO, otherwise they would close outgoing SMTP port (25), but Telia did not do this… so Telia users can continue to spam if they want – but it is traceable and Telia’s abuse group can take care about it.

·        Then probably because of “open relay” SMTP servers. – YES, that must be the right reason. Closing incoming SMTP port (25) prevents Telia internet users that has SMTP servers to relay spam.  


Let take a closer look, what is it mean: open relay SMTP server.

SMTP (Small Mail Transfer Protocol) – described in RFC 821, is the most popular protocol for exchanging e-mail over Internet. It requites two SMTP servers that after negotiation, transfer mail from one host to another – trying to reach the final recipient in order to deliver e-mail. Sometimes it is not so easy, because recipient could be situated in deeper inner network, therefore main SMTP server have to route and relay the post to other SMTP server until it comes to destination. SMTP server needs to relay “unknown hosts” as well if ISP wants to provide POP/SMTP services without any extra effort.

This behavior of SMTP servers could be abused by malicious spammers that use servers that do not have relay control, to send unsolicited mail in somebody else name, by using other – usually innocent SMTP server.

It is a real problem that everybody has to be aware. You may find more information about spam and open relay at


What should the SMTP administrator do?

Every system administrator who operates an SMTP server should take responsibility for server relay rules.

·        The best way is to disallow relay from the Internet. Most users does not need it at all.

·        If system provides POP or IMAP access, then the best way is to use POP3/IMAP before SMTP authentication mechanism, that will allow users to send without open relay

·        There are other mechanism that could be used by configuration of SMTP server as MAPS etc.


What could Telia do?

Yes, closing the incoming SMTP port (25) was the easiest way to prevent to use Telia network for open relay, in hope that customers will just swallow the decision.

Another way could be to monitor the traffic or better scan the Telia internal network for open relay SMTP servers and send them a note about security holes.


I am convinced that most of “open relay server owners” was not aware of their server odd behavior, because, unfortunately, all older Linux distributions come with open relay sendmail. Moreover sendmail package is in the basic kit, so most of the Linux beginners run it without knowing that it is running.

To be honest, I feel myself responsible because of it, because I wrote, few years ago, in Cable-Modem HOWTO the Com Hem chapter, that describes how to connect Linux box – if Com Hem had not given any Linux support.



And third… if we accept that Telia should close incoming SMTP port (25) anyway, then Telia could do it in more customer friendly way. As:

  • Send out a note few months earlier
  • Offer alternative solution from slightly higher price


I work as security expert in one international company that provides lottery services worldwide. As a person that works more than ten years in IT branch - I know what I am talking about, and usually I do not shout without a reason.

Half of my life I spent in development for open source and GNU projects, building positive approach among Internet users, creating competence in operating systems and is my favorite hobby project, which achieved respect for services and competence world wide.


I know that it is hard time for IT industry in Sweden. Companies are suffering of competence shortage. Anyhow, before some action than affect whole service quality and hundreds of thousand of customers, Telia should think about reputation, customers and share-holders opinion that can affect Telia's economy as well.


It would be a pity if sites like, disappear from Internet because of such ridiculous reasons of incompetence. Therefore, I hereby, offer part of my time, for free, to solve security issues like this, if needed - if Telia, self can not cope with them in customer friendly and human way.


Thank you for attention, and hope that Telia will give back SMTP port (25) for at least few weeks, giving time to (and other Telia customers) to reorganize mail services to be able to continue operation in some way.




Zoltan Arpadffy                                                                            owner and system manager
 (can not reply any more)

Telia kundnummer: 108 310 097

Villaägarnas medlemsnummer: 341605




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Jag skulle kunna skriva detta brev på svenska också, tyvärr, mina kunskaper att uttrycka åsikter på rätt sätt på svenska är ganska begränsad.