Sending mail over IPv6? Authenticate!

Josh over at Word to the Wise explains that as Microsoft brings live IPv6 support for its Office365/Exchange Online Protection email platforms, they're mandating that all mail sent over IPv6 must authenticate with either Sender Policy Framework (SPF) or DomainKeys Identified Mail (DKIM). Unauthenticated mail will be rejected. Read more about it here.

Domains and have been retired

If you're trying to send mail to subscribers at or today, you'll notice that all delivery attempts are being rejected, because wireless data provider Clearwire has retired all email services as of April 15, 2015.

Once upon a time, Sprint was the biggest investor in Clearwire, and Sprint's 4G data service was provided over the Clear WiMAX network. Sprint fully acquired Clearwire in 2013, and announced that it would be shutting down the Clear network sometime in 2015. It stands to reason that this email domain retirement is likely related to that overall acquisition and service shutdown.

I was not able to find any information related to the transition of or subscribers to other domains. Deliverability Support Form

Lots of folks seem to have an outdated bookmark (or have found an outdated link) for the (aka Microsoft Hotmail) deliverability assistance request form.

Here's the correct link (as of June 2015):

For information on how to troubleshoot deliverability issues when sending to, visit the Postmaster website. Their Troubleshooting page may be of particular interest.

More Jobs @ the Litmus Job Board

Looking for other, non-deliverability related email jobs? Check out the Litmus Job Board.

Troubleshooting AOL Deliverability Issues

Update: As of May, 2018, this information is now out of date, due to the consolidation of the AOL and Yahoo webmail platforms under their new "Oath" umbrella. Click here for my thoughts on how to troubleshoot AOL deliverability issues at this time

A client asked me the other day, how do I go about troubleshooting AOL deliverability issues? Since AOL is an ISP where (for the most part) it's easy to solve deliverability issues, I thought I would share some general guidance here, to make it easy for people to get started.

If you're having trouble delivering mail to AOL, it tends to be one of these three things.
  1. Is your IP address whitelisted with AOL? Most ESPs manage this process for you, and most of them have probably submitted all, or big groups of their IP addresses, to AOL for whitelisting already. But, stuff happens. AOL doesn't tell you if your IP address falls off of their whitelist. Ask your ESP to check this for you. Ask them to resubmit your IP address to the AOL whitelist. If it is already whitelisted, the attempt will fail with a simple "this address is already whitelisted" error, and then you'll know. If you send on your own, not using an ESP, here's where you can find more information about the AOL whitelist.
  2. Are you set up with AOL's Feedback Loop? A feedback loop (FBL) is what allows you to receive a complaint back from a subscriber, when they click the "this is spam" or "junk" button inside of a webmail's user interface. AOL and many other ISPs over FBLs. They indirectly (but importantly) help with your deliverability by allowing you to cease mailing people who complain; preventing repeat complaints. More importantly, if you have an excess of spam complaints, they help you tie complaint numbers back to specific segments or processes that you may need to refine or retire if you want to stay in AOL's good graces (and in the inbox). Like with whitelisting, ESPs tend to manage this process for you. Ask your ESP to help you confirm that your AOL FBL is set up properly and working. Check your ESP's user interface to scan for unsubscribes or complaints that would have been delivered back to you via that FBL. And if you send on your own, not using an ESP, learn more about and sign up for the AOL FBL here.

    (An important note for ESP users: Do not sign up for the AOL FBL yourself unless your ESP has given you permission to do so. Your FBL signup attempt can interfere with the ESP's own attempt to manage this process for you. Bad things can happen, like you could accidentally redirect spam complaints to somebody at your company, who won't know what to do with them. Complaining subscribers will not get unsubscribed, and your deliverability will suffer.)
  3. Is your spam complaint rate just too darn high? I don't exactly know what constitutes "too high a complaint rate" in 2015. AOL used to publish a threshold of .1% as an allowed complaint rate. Later it was .3%. A quick Google search isn't finding me any updated numbers. Regardless, the AOL bounce error message would probably give you some insight to whether or not excessive complaints are at issue. A common block is "554 RLY:B1" which does indeed indicate that your mail is generating too high a complaint rate as measure by AOL. How do you fix that? Try to tie complaints back to specific segments or processes. If one generates more complaints than others, that may be the culprit. The devil can be in the details, so it might be wise to engage a deliverability consultant for assistance. (AOL does publish some fairly good-but-high-level sender best practice guidelines as well.)
How do I know if I have a good sending reputation at AOL? Here's a link to AOL's IP reputation lookup form. Plug in your sending IP address and their system will tell you its opinion of the mail being sent from that IP address.

Do other ISPs have reputation lookup tools, feedback loops, and postmaster websites? My friend Laura Atkins over at Word to the Wise has put together an excellent matrix listing all of the different ISP resource details and links that she is aware of. This is well worth bookmarking.

Do you have additional insight to share with regard to troubleshooting AOL deliverability issues? Please share in comments.

Are you hiring for deliverability?

I know a few folks who are looking for deliverability-related positions due to layoffs and downsizing at various companies recently. Are you hiring? Feel free to drop me a line and I'll be happy to post your job opening here on Spam Resource for free.