May 1, 2007
Updated: June 11, 2007 (added reference to thread on SPF mailing list)
Updated: June 15, 2007 (I've found a workaround!)
Updated: January 28, 2008 (workaround modified, configuration posted)
In recent months, Hotmail has been blocking delivery of most messages from projectile.ca to their mail servers. We're not the only domain affected by this; in fact, it seems to be a very wide spread problem. The Register published an article about it today: Hotmail's antispam measures snuff out legit emails, too.
Sympatico outsourced their residential email services to Microsoft's Hotmail, starting in 2004. Hotmail's over-eager filters appear to be running on at least some Sympatico addresses, as well. This also applies to email addresses on Microsoft's other free web mail domains, msn.com and live.com.
Thanks to Mike Cardwell on the Exim-users mailing list, a workaround for this problem has been found. It's a pretty skanky hack, involving messing with some of the message headers. This seems to allow the hotmail messages to be delivered, for the time being at least.
It's worth noting that my first test message with this workaround in place did end up in the Junk folder, so you'll still need to add our addresses to your address book on Hotmail to ensure deliverability.
This feels very fragile to me. I would not be surprised at all if this hack stops working at some point. My recommendations below of switching to a more reliable free webmail provider still apply.
# For outgoing messages to hotmail servers, add references/in-reply-to
# headers to make it look like a reply, and strip the Thunderbird
# User-Agent header.
hotmail_headers:
debug_print = "R: hotmail_headers for $local_part@$domain"
driver = redirect
domains = hotmail.com : hotmail.co.uk : hotmail.fr : hotmail.it : \
hotmail.de : hotmail.ca : sympatico.ca
headers_remove = User-Agent
headers_add = ${if !def:h_References: \
{References: <BAY000-000000000000000000000000000@phx.gbl>\n}}\
${if !def:h_In-Reply-To: \
{In-Reply-To: <BAY000-000000000000000000000000000@phx.gbl>\n}}
data = $local_part@$domain
There doesn't appear to be anything I can do to get Hotmail to reliably deliver email from projectile.ca. At this point, I'm recommending that you consider switching your email account to Google's Gmail or Yahoo Mail.
Sorry for the inconvenience.
I've been in contact with Hotmail Support about this issue, and the reply I got from them on April 30 is quite similar to the answers described in the Register article:
Hello Marc,
We have identified that messages from your IP 64.26.176.14 are being filtered based on the recommendations of the SmartScreen filter. SmartScreen is the spam filtering technology developed and operated by Microsoft. SmartScreen is built around the technology of machine learning. SmartScreen's filters are trained to recognize what is spam and what isn't spam. In short, we filter incoming emails that look like spam. I am not able to go into any specific details about what these filters specifically entail, as this would render them useless.
We are investigating the filtering issues you are having. We shall contact you once we have our findings.
However, we also base our spam rating on the reputation of the sender. One way to positively impact the reputation of your IP is to obtain SPF/Sender ID records. This technology allows SmartScreen to better track emails from your IP, weeding out spoofed messages. I see that you are using "?all " in your SPF record. Hotmail does not really like the "?" I would suggest "~all" or "-all". This may not fix your issue as you are being hard filtered. . We are investigating the filtering issues you are having. We shall contact you once we have our findings.
In the mean time here are some issues that you can look into fixing while you wait.
Please confirm that your emails comply with MSN Hotmail's technical standards. This information can be found at: http://postmaster.live.com/Guidelines.aspx <http://advertising.msn.com/adproducts/Email_TechStd.asp>
It will also be helpful to send example emails to randomtestacct@hotmail.com <mailto:randomtestacct@hotmail.com> from your MTA so that we can examine the types of emails that you send. This will help me in our investigation. When you do this please send me the subject lines of emails you have sent. Please make sure that these emails are functionally similar to the types of emails that originate from your system, as any deviation from this may hinder our ability to investigate your problem. Do not use the word, "Test" or anything that would change the email from the original message that was initially sent to Hotmail Customers.
I hope that the information that I have provided to you has been helpful. You may also be able to find additional information on common delivery questions at the Hotmail Postmaster Site found at: http://postmaster.msn.com/. I would like to highlight some key areas which I believe are appropriate to your company.
* Hotmail has created the Smart Network Data Services program. This is a service that helps legitimate email senders work with their customers and partners to reduce spam originating from their IP. http://postmaster.msn.com/snds/ <http://postmaster.msn.com/snds/> . This program allows a sender to monitor the 'health' of their IPs.
While using the SNDS tool, enrollment in the JMRP or having your IPs registered with Sender ID will not allow emails from your mail servers to bypass our filters, these are in place to help legitimate companies deliver their emails to Hotmail Customers.
* SenderScore Certified Mail Program. Many legitimate mailers and marketers have qualified and joined this "white listing" program to improve mail deliverability and decrease email from being filtered to the Junk E-mail Folder. Sender Score is a third party program, administered by Return Path. Sender Score (www.senderscorecertified.com <http://www.senderscorecertified.com/> ) is the only White Listing service to which we subscribe.
The troubleshooting steps in this email are recommendations only. Microsoft makes no guarantees that following these steps will guarantee deliverability to MSN, Hotmail, or Live.com customers.
Sincerely,
Dallas
Windows Live Hotmail Domain Support
After reading others' experiences with this issue, I don't expect to hear back from Hotmail support with any further assistance. If I do, I will update this page.