Last month I blogged about Microsoft protecting Hotmail from Spam and blocking the world. This month we’ve got some updates, and useful links.
The following is a slightly edited version of a post by BuildaSkill member GazLanNaThai, originally posted on the community forums at www.eBid.tv - many thanks to Gaz for the heads-up, and permission to post it here, it saves me writing a post.
We’ve been having a major issue at this end with our mail servers not getting emails through to specific mail hosts - in particular Hotmail, MSN, gmail, AOL, and more recently several others. It came to a head in October 2007 when we noticed our mails were being returned as blocked by several private domain names. The Non-Delivery Record (NDR) gave an SMTP:5.0.0 error message, though the text note varied.
(Ed - same problem as we’ve been having, and the reason for the original blog post)
The prime problem appears if you have the following email setup -
1 - You use a broadband, ISDN, or fixed line connection to the internet, and
2 - you have your own internet domain name, and
3 - you host an internal mail server (e.g. MS Exchange or similar) at home or office
If you use only “Internet mail” through XP / Vista, or similar, on a single PC, you are very unlikely to be affected.
If you have a network of several PCs and use only direct “Internet email” (i.e. each PC uses your ISP mail server settings in Outlook etc) then you are unlikely to be affected.
Problem -
When sending email out to specific domains you get the problem above, but you are able to send email to domains such as eBid, eBay, or to Yahoo or other popular ISP mail users such as BTinternet, BlueYonder etc. But all email to Hotmail, gmail, AOL etc is getting bounced back.
This might be because the recipient has you in their spam list, but it is more likely to be because of a new anti-spam initiative called “SenderID” (by Microsoft and friends), or “Sender Policy File” (SPF) by the wider internet community.
SenderID and SPF are slightly different, but essentially do the same thing in the same way using the same protocols - unless you are a deep level techie, don’t worry about the difference - it only really affects massive corporate networks.
INFO SOURCES
The first thing you need to do is to identify if you’re likely to be directly affected.
The easiest way to do this is to go to www.spamhaus.org and click on the PBL link in the top middle of the header.
Then get your current IP address from your ADSL router or similar - this is the IP address your ISP gives to you each time your router connects to them (it changes each time).
On the spamhaus PBL page, at the top of the left margin is a box to check your IP address - copy and paste, or type, your IP address into it and click the button to check your IP.
If it returns a page with three green links, Great! It doesn’t affect you (today).
If one or more of them are red - then BOO!!!! you’re on the block list - and it’s probably not because of anything you’ve done, but because of what someone who previously had that IP address, has done.
Now you have to start studying - SpamHaus contains lots of reading material, and if you’re in anyway PC-techie, you need to read it all. It’s a little heavy, but fairly straightforward if you have any IT Support experience.
SOLUTIONS
You’ll find that SpamHaus refers you to a Microsoft page www.microsoft.com/senderid/wizard - be very, very, VERY, careful if you use it. It’s unbelievably easy to make a complete and utter mess of your ability to send or receive emails through your internal server (I know! Been there, done it, got the t-shirt, broke my server
).
If you create a SenderID-SPF file using that wizard, BE WARNED - you DO NOT add it to your internal server’s DNS zones - it goes to your ISP for them to add to THEIR DNS server.
OPENSPF - OpenSPF are the original team who began developing the SPF anti-spam global system (typically Microsoft hijacked their idea and then began customising it to make it proprietary to Microsoft technologies, just like they did with SQL and other technologies).
www.openspf.org contains lots of info about the technology, from the originators, in both plain language and tech-speak - you can choose how deep you want to learn about it. They also have a wizard ( www.openspf.org/wizard.html ) that does the same as the microsoft one, but it creates a truly universal SPF file - one that can be used on UNIX / LINUX as well as Microsoft servers and other less common server systems. Their “SenderID vs SPF” page explains the differences in full, and makes a complling case for using the OpenSPF version.
READ the info pages before implementing - again, the SPF file created gets sent to your ISP - do not add it to your own server unless you’re on a permanent IP with fixed line connection.
Once your SPF file is in place at your ISP, and their DNS server has promulgated it around the world (allow 12-24 hours) you should get no more issues with Hotmail & co bouncing your emails due to “anonymous access” issues (read the sites mentioned to understand that).
Any tech questions - please refer to the sites stated, or your ISP support division. If you ask me for any support, you’ll have to pay for it. Your ISP’s will likely give you support for free.
Original content by Gaz, slightly edited by Ed.
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