Have you ever wondered why senders complain so much about Yahoo Mail’s poor delivery?

So did Email Battles.

Curious, we pointed our hot new diagnostic toy, Mail Server Profiler, at Yahoo’s mail servers, to see if we could find any hints.

First, Mail Server Profiler mapped and analyzed the Yahoo Mail setup. It found 16 host IP addresses behind four mail server MX records, and identified half of them as closed, ie, not accepting any email messages.

Yahoo Mail Family Portrait[Yahoo Mail MX Records, 12 April 2006, 13:04 CST; Mail Server Profiler<br /> Screenshot]”></center><br /> Next, we took measurements every two minutes for half an hour. That’s 15 separate readings of each of 16 IP addresses, for a total of 240 readings. The results were surprising.</p>
<p> During that period, Yahoo mail servers were willing to accept mail just 55% of the time (133 “open” readings). Average availability for MX record groups over the period ranged from as low as 25% to a high of just 75%.</p>
<p><center><b>Yahoo Mail MX: Mean Availability Over 30 Minutes</b></center><br />
<table align= MX Server Group Availability mx1.mail.yahoo.com 63% mx2.mail.yahoo.com 75% mx3.mail.yahoo.com 41% mx4.mail.yahoo.com 25% All Mail Servers 55%

In fact, only one of the 16 hosts was open for every reading. The worst host was available 7% of the time.

What does this mean to the average sender? Many network managers set their email serving software to re-try sending four times, at increasing intervals. For example, after the first attempt, you may try again in 10 minutes. If that attempt fails, try again an hour later… again in 4 hours … and last attempt, 10 hours after that.

This Is Yahoo’s MX Accessibility? Yikes![Yahoo Mail Server Response Graph]

If your chances of delivery are less than 60% each time you try, you may fail to get messages delivered at all. In the meantime, as ever more undelivered mail piles up in its delivery queue, your server will waste more and more storage, bandwidth and cpu cycles trying to ship the messages. Bad karma.

So what’s the answer? Paying customers who don’t want to maintain their own in-house mail servers, but still like reliable email, may want to consider moving their accounts to healthier environs, like Fastmail or USA.net. Free account holders know where to go.

And frustrated senders who are already paying to deliver Yahoo Mail via clock cycles and bandwidth? Boy, does Yahoo have a deal for you. Soon, for just a few dollars per million, you can become a certified sender, and Yahoo will start delivering your mail almost as efficiently as every other email service provider on the planet.

Capiche?

Email Battles Backgrounder: