About 240,000 of them are “old” (inactive) subscribers. About 70,000 are relatively “new” (active) subscribers.

They recently segmented their list and sent the same newsletter to each group (separately) over the same IP address, about 6 hrs apart from each other. Around 2pm, they sent the newsletter to the large, inactive list. Around 8pm, they sent the same newsletter to the active list.

The results are eye-opening…

Stats for the “Inactives” list (241,832 recipients):

Spam Complaints: 43
Open Rate: 6%
Click Rate: 2.4% (and 7,688 total clicks)
Unsubscribes: 264
Bounces: 6,878 (2.8%)

Stats for the “Actives” list (69,642 recipients):

Spam Complaints: 3
Open Rate: 36.3%
Click Rate: 7.4% (and 6,925 total clicks)
Unsubscribes: 96
Bounces: 128 (0.18%)

The number of bounces for the “old-members-list” is what I’d call very high. The number of abuse reports (43) is what I’d call disturbing. These are humans clicking the “this is spam” button for a run-of-the-mill company newsletter.

More interesting is what happened to their deliverability for the old list. We measured it using ReturnPath’s Mailbox Monitor service. Here’s a screenshot:

As you can see, their emails went 100% missing from AOL and Hotmail, 80% from Yahoo, and 70% for Comcast.

Also, it’s almost a day later, and 20% of the “sent-to-old-members” list still hasn’t been delivered to Yahoo, because they keep getting deferred.

My guess is the sheer number of spam reports from the old list is what got them blocked, and therefore their emails have gone missing (here’s some explanation from AOL on how they measure IP reputation).

If you’ve got a bad reputation, you’ll get blocked by AOL (and most of the major ISPs). Comcast’s Postmaster lists how emails get throttled based on your “Sender Score.” The lower your score, the slower you’ll get delivered.

So how is your score determined?

AOL measures your IP reputation by:

• Spam complaints (from humans clicking the “spam button”)
• Spam filter triggers
• Bounces from undeliverable addresss (i.e. old lists)

I wish we had deliverability stats to show you how the “active-members-only” went, but we forgot to track the good one (d’oh). Maybe next time.

Even without a side-by-side deliverability comparison, the end result is clear: old lists suck.

They generate too many abuse complaints, which can get your entire campaign blocked by ISPs. Then, the active members who want your emails never get your message.

Related Stories:

• Desperation Marketing (see “living dead”)
• Why your email won’t get delivered
• ReturnPath’s Deliverability Best Practices Guide (PDF)
• Effects of old email lists (an oldie but goodie)

Ever thought about segmenting your email campaigns so that they only go to the “active” members on your list? Here’s how to do that in MailChimp.

He gave me some tips that I could pass on to our readers. So here you go:

• Comcast really, really hates it when you send to an old list (with lots of undeliverable email addresses). If you’ve got too many emails on your list that no longer exist, Comcast will block your IP address. This is a very strong argument for cleaning old, inactive members from your lists. Yes, I know it feels safer to keep old members on the list, because the number of recipients looks so much bigger. Yes, I know your boss keeps telling you not to clean your list, because they don’t want to lose any prospects. But those bad addresses are just holding back your overall deliverability and keeping the good addresses on your list from getting your message. Yes, I have numbers to prove it. In a later post.
• Comcast doesn’t like it if you send too many emails all at once to them (this one’s kind of a no-brainer). Here’s what makes them different: they’ll actually TELL you how many you’re allowed to send at once.
• As you can see from this chart, the rate of emails you’re allowed to send to Comcast at once depends on your IP’s “reputation.”
• Your IP reputation is based on at least two factors: Authentication (a technology standard that’s used to prove an email is not a forgery), and the IP’s “Sender Score” (Your IP’s Sender Score is kind of like a credit rating, and it’s the folks at ReturnPath who issue the score). MailChimp customers – Authentication is free with every MailChimp account, and through our relationship with ReturnPath we monitor our senderscore closely.

For those of you familiar with ISPs and abuse desks in general, none of this is all that new. The interesting stuff is how forthcoming and helpful Comcast is with their error codes and rate limiting charts. Overall, their new Postmaster site is one of the best I’ve ever seen (look at all the handy RSS feeds):

http://postmaster.comcast.net/

If you’re new to all this, and wonder how this applies to you:

• Don’t send to old email addresses. You’ll get yourself (and other innocent senders) blocked.
• At some ISPs, old email addresses get turned into spam traps. You send an email to a spamtrap, and you are instantly blocked. We had a case of a MailChimp user who sent to a 10-yr old email list (totally opt-in, and the guy luckily had IP/timestamps on all subscribers) and one of the addresses had been turned into a spam trap. The impact on his deliverability from a spamtrap hit was instantaneous and dramatic. Keeping his proof of opt-in for so long saved his behind.
• If you’re sending your emails from an ESP (like MailChimp, Constant Contact, etc) that has shared IP ranges, then one bad apple can truly spoil the whole IP range. So it’s important to go with an ESP that closely monitors their deliverability, and punishes bad senders (it’s for the greater good). Quality over quantity.
• Don’t export your entire email address book and assume they all want to receive email newsletters from you. Address book dumps are full of old email addresses, and are one of the most common reasons I see senders get blocked. Other reasons include: Fish bowls, sharing lists, and buying lists.
• If you have an old list of people who opted-in to receive emails from you, but you haven’t sent them an email in a really long time (or ever), then you need to delete any emails older than 1yr, then send the remaining subscribers a “remember me?” welcome email. Here’s a good example.
• If you send emails on a regular basis, and you think your system is cleaning the list for you, you still might want to segment your list by actives vs. inactives.

Comcast isn’t the only ISP that hates it when you send to old/dead lists.  AOL’s postmaster talks about IP reputation and undeliverables here. ReturnPath, the experts on email deliverability, mentions undeliverables here and offers some tips. Laura Atkins from WordtotheWise talks about “Letting Go” of old members.

In general, there’s a shift (again) in the way ISPs and email receivers judge emails as spam or not. Instead of relying on blacklists or focusing on bad content, they’re looking at your overall reputation as a sender. And list cleanliness (undeliverables, hard bounces, spam complaints) are huge factors in determining how clean your list is.