Outlook.com - New Email Server IP Address

Question asked by CCWH - 4/7/2015 at 3:08 PM

Unanswered

Hello all,

I have been through this before but wanted to check if there is now an easier way....

Just set up a new SM server. Initial tests to an @outlook.com address results in an immediate bounceback:

Reason: Remote host said: 550 OU-002 (SNT004-MC4F26) Unfortunately, messages from 78.157.211.172 weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors

Looks like the IP block we have received has a bad rep with the Outlook.com servers.

So, apart from going through their SNDS request is there anything else that can be done?

Just to note, the IP address is not on any public block/abuse lists and the sending server is doing all it can!

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Bruce Barnes Replied

4/7/2015 at 8:08 PM

We went through this with another high-volume client and were told that they had to implement DMARC before removal would be considered.

This was, allegedly, because of complaints from hotmail.com users, who are now a part of outlook.com.

Bruce Barnes ChicagoNetTech Inc brucecnt@comcast.net Phonr: (773) 491-9019 Phone: (224) 444-0169 E-Mail and DNS Security Specialist Network Security Specialist Customer Service Portal: https://portal.chicagonettech.com Website: https://www.ChicagoNetTech.com Security Blog: http://networkbastion.blogspot.com/ Web and E-Mail Hosting, E-Mail Security and Consulting

CCWH Replied

4/7/2015 at 11:59 PM

Thanks Bruce. We do implement DMARC but didn't on the test domain. I'll sort that and see if it helps. Thanks.

Joe Burkhead Replied

4/10/2015 at 11:27 AM

Strange, I have not implemented DMARC yet and don't have any problems sending to outlook.com , in fact I have an outlook.com address and occasionally test it to make sure it still works.

Joe

Bruce Barnes Replied

4/10/2015 at 11:41 AM

Outlook.com officially adopted DMARC in 2012, but did not start checking until August, 2014. Now that they've brought Hotmail.com, and some of the other offshoots of Microsoft's paid and free e-mail services under the Outlook.com hosting umbrella, they are starting to vet the incoming e-mail with much more scrutiny.

From a comment to the article, "Outlook.com Tests the DMARC Waters" (published 29 July, 2014) on The E-Mail Skinny,

[Terry Zinc: 30 July, 2014] ]I was the one responsible for making that change (i.e., suggesting it and getting others to agree) to the DMARC record for outlook.com.

I agree that publishing a DMARC policy of p=none is frequently a step towards moving to p=quarantine or p=reject. However, this move was not specifically meant for that.

Instead, outlook.com is moving to consolidate its SPF record as it merges with Office 365. This move is used to determine which IPs are actively used to send email that passes SPF with the goal of removing IP ranges that are not actually used. DMARC is a great tool for doing that.

But, thanks for noticing!

NOTE: Terry Zinc is the tech at Outlook.com who is overseeing Outlook.com's implementation of DMARC

CCWH Replied

4/11/2015 at 12:25 AM

Just to add to this, having DMARC has greatly increased our IP trustworthiness. Especially with the larger receivers such as Google, MS, AOL etc. This issue turned out to be the IP address was listed with Symantec mail block system which Outlook.com seem to now use. This only showed up using the Check IP Status within the SNDS account. Easy to remove the IP and now all resolved.

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