Can’t Keep Up? 9 Ways to Simplify Your Path to the Recipient’s Inbox

How ISPs Gamble with Your Reputation

Email marketing is about the balance between strategy, deliverability, funding, process, staffing, and the need of the customer. There is a whole set of things that influence the final decision. Deliverability is just one of them.

When you are making a decision about re-activating customers, sending that next promotional, transactional or welcome email, deliverability becomes one of the things for making that choice.

You can test your email deliverability right now using this email spam checker and find out how different mailbox providers treat you and your emails.

If you don’t have a lot of problems with deliverability, then… you are a rock star!

However, have you ever wondered what determines whether or not your email will be sent to the recipient’s Inbox, or filtered as junk mail, or blocked?

To help you understand email deliverability at major Internet service providers Comcast, Microsoft, AOL, and Gmail, I reveal the main practices (all shared by the ISP’s representatives at different webinars) these ISPs apply in terms of list quality, sender reputation, and recipient engagement. Also, to make it easy, I broke it down into 9 questions/answers.

You’ll get a clear understanding of how these ISPs treat inactive accounts, what they think about engagement and how they measure it, how they determine “inactive” users, whether or not inactive users harm deliverability, and what ISPs think about the email open rate and dedicated/shared IP addresses.

So, let’s dive right in.

Is it true that ISPs turn abandoned email accounts into spam traps? Email marketers used to believe it, but is it actually true?

You know it’s partially true with AOL. But, whenever they did it, they never used the accounts that have been abandoned or canceled. Instead, they’ve been using accounts that have been dead and unable to receive mail for one or more years.

Guys at AOL know that anybody who was actually doing list management or making sure they cleaned up their list properly, shouldn’t ever be sending emails to these accounts. They also know which accounts used to be real and which accounts have been set up as spam traps and have never been signed up for email lists.

Comcast, Microsoft, and Gmail do not convert abandoned accounts into spam traps (it seems I’m debunking a myth right now!). However, if you are sending to many inactive accounts, it will impact your overall reputation as a sender with these providers.

Therefore, best email marketing practices teach to keep the list up-to-date and remove inactive users to avoid hitting spam traps.

People have different types of viewing habits. There are those who are engaged in their inbox and those who are not. How do ISPs determine inactive users?

Obviously, an inactive user is somebody who’s mailbox is turned off. AOL keeps an eye on how often somebody logs in, and if a user does not log in for a hundred eighty days, the user’s mailbox will be turned off. Whenever you try to send an email to a customer whose mailbox is inactive or have never existed, emails will return an SMTP error with the 550 SMTP error code.

Comcast, AOL, Microsoft, and Gmail look at explicit actions. Even if the customers do continue to log in to their accounts, ISPs pay attention to whether or not they open or file emails, and see which emails present interest to the person and which don’t. Providers also know when the customers are just logging in on their phones.

The phone checks mail all the time, but some people never do anything else: they never send, move, or delete anything. Basically, they have just forgotten to stop accessing that mailbox. And when ISPs stop seeing a customer interaction, they are considered inactive.

Is there a good reason for email marketers to remove inactive users from their list? What is the recommended period of time to consider the user as inactive?

Removing inactive users is going to help you in terms of your deliverability to any ISP.

In many cases, email marketers have a clear understanding of whether or not people are opening and clicking their emails. There is a point at which it’s not worth it for you to continue trying to re-engage some customers – they are just not interested.

If you don’t have those kinds of metrics, and you haven’t figured out what that point of diminishing return is, spend some time to do it because it will save you from trouble in the long run.

One of the things the bad guys do is they send mail to accounts they own trying to pump up their volume. So, when they come around later on trying to send their spin run, it looks like they established usability of the service. We pay attention to the fact that they are sending mail to accounts that never do anything with mail. So, having a large number of recipients on your mailing that do not interact with you at all is a negative feature.

It’s not gonna kill you if you do it once in a while, but it you do it repeatedly, if it’s habitual, especially if some of those members you’re trying to send mail to don’t exist anymore, and you’re sending to a lot of dead accounts, those are gonna cause you problems,

Paul Rock,
AOL Principal Programmer/Analyst,
the “Mythbusters: Deliverability vs Engagement” webinar,
March 17, 2015.

If you start thinking about the period that you want to deal with, figure out what the expiration of a mail account is. All services are different. So, maybe it’s a year of inactivity, maybe more. The time frame really depends on the frequency of your emailing. If you’re sending mail one or two times a month, it is reasonable to consider a longer period, for example, 1,5-2 years. If you’re emailing quite often, every week or several times a week, you should shorten the period of inactivity to 6-12 months.

You just need to track your recipient engagement to have a clear understanding of what users on your list are no longer interacting and remove them immediately.

Will ISPs shut down the user’s account after a certain time of inactivity and stop accepting mail for that user?

The way the ISPs treat inactive accounts is different. While Comcast and Gmail do not cancel accounts, AOL will turn off the user’s mailbox if the user did not log in within the last 180 days. They will stop accepting mail for that user and return the 550 SMTP error whenever you try to send an email to the user.

At Microsoft, it’s purely based on when you login in a certain time frame. If you stay logged in during a minute roughly within a year, then they can hibernate the account. But they don’t do that immediately, they give an additional grace period (but not too much), due to privacy concerns.

There is a huge number of accounts that are created on both free and paid email services. Some of them are spam accounts. If you are trying to use a Microsoft account to send out spam, they will delete it, but they do not nuke good active accounts.

What attributes do ISPs use to determine recipient engagement? Does engagement impact reputation?

Email marketers used to measure engagement based on email opens and link clicks.

With ISPs, it’s a little different. They track a lot of other interaction features: forwards, replies, marked as spam, address book adds, moving to the junk folder, or marking ‘this is not spam’, deletes without opening.

Things like that tell Internet providers a lot about what the customer has done with the email and give them a level of the customer’s engagement, which then directly impacts the sender’s reputation.

Every time we get a certain amount of spam markings from our users, reputation goes down. And as we get non-spam markings that is when users move emails from the Junk folder to the Inbox, they [senders] get some positive reputation. That’s how it looks”,

Sri Somanchi,
Gmail’s Anti-Spam Product Manager,
the “Mythbusters: Deliverability vs Engagement” webinar,
March 17, 2015.

At Gmail, engagement is seen as the sum of the total user’s actions upon the email. They track explicit user’s actions and they have a direct relation to how they classify the email.

Also, Gmail looks at implicit signals like email opens and other interactions of such kind to determine how they personalize the email class for a given user. These implicit signals are very important because they make sure that your email is reaching the end user.

With, it’s done on a personal basis, and how users behave upon explicit actions is not necessarily damaging or increasing the overall reputation of your domain and your IP address. With, it’s about knowing whether or not you reached a specific customer Your test accounts may show it got delivered, but if somebody else has been deleting your junk mail for weeks, your email is not getting to that user.

Simply speaking, if people are engaging in your mail, it increases the likelihood of the “dog” deliverability within their specific Inbox, but not necessarily broadly.

Overall Internet service providers primarily look at explicit actions users take on emails to measure the level of engagement of their customers with your emails and determine your overall server reputation. Yet, implicit actions matter for some providers too, in terms of email classification for a particular user.

Will it be right to send a campaign aiming explicitly to get recipients to reply or to open a message in order to improve your engagement reputation?

It may seem odd but from the point of view of Internet service providers, there is nothing wrong with sending such a campaign.

There’s always going to be the case when you are sending just informational or transactional mailings, and there is not really much for your recipients to do with such emails. Asking to somehow interact with the message can be good for your recipients.

Although, while looking for ways to ask recipients to reply, don’t write something like: “Reply to me if you don’t want to get this mail and then want to get off the list.” It is a bad emailing practice.

Instead, consider this option: “Hi, if you see this email and want to make sure you’ll get other emails from me, please save my email address to your address book”.

A Dedicated IP address vs a Shared IP address. What is better?

I would say that a dedicated IP is better, and here is why.

Recipients are going to hold senders accountable for the quality of their emails. Unfortunately, the sender can’t hold the author accountable for the quality of their emails. Even if you’re doing mailings for fifty different brands, all campaigns are coming from the same IP address.

If the IP is shared, a sender with low-quality, spammy emails will harm every other sender from this IP. It’s like they say: a bad sheep spoils the whole herd. If a brand has a dedicated IP address, it is fully responsible for the quality and reputation of this IP.

The same goes for Internet providers. When they have different customers, it’s much easier to track and manage them on individual IPs. They personally pay the price when they get overly aggressive.

Even within a brand, you might want to consider having a dedicated IP address for your transactional emails separately from the marketing emails. Transactional emails inherently have a good reputation and you wouldn’t want a bad email marketing campaign to impact the deliverability of your transactional emails.

Note: keep in mind that a dedicated IP is more costly, and would be suitable only for businesses with large sending volumes.

Read more: Dedicated vs Shared IPs: Which Should You Choose for Better Deliverability

What are the main things email marketers should pay attention to in order to establish a good reputation with ISPs and get high deliverability?

Below is the summary of recommendations from ISPs that you want to adopt to look like a good sender for them. You are most likely aware of some (if not all) of the practices. If some are new to you, take the time to adopt them.

    1. Always seek explicit permission from the user with more specific options.No pre-checked boxes. Make sure the user clearly understands what they sign up for.
    2. Make sure it’s very clear who you are.Make sure that your brand is reflecting in the emails.
    3. Send a type of email that your recipients signed up for and want to receive.Do not send a lot of other things just because you got permission.
    4. Sign up for feedback loops.So you can see what’s causing you the mystery.
    5. Set up email authentication.As Paul Rock, AOL’s Principal Programmer, said:

      If you don’t have a reputation, you have a bad reputation. 98% of new IP addresses we see are spewing garbage. We don’t know you – that’s the problem. And the only way we can know you reliably and know that you are not somebody pretending to be you is to make sure you are authenticated. Without authentication, we don’t know you.

    6. Use the right metrics.Measure your clicks, opens, and basically, everything you can. Compare these metrics across campaigns to see the performance difference.
    7. Measure your Inbox delivery rate.Let’s say your email service provider is reporting 100% deliverability with a 0% bounce rate. It looks like 100% deliverability but it may be 95% Inbox placements and 5% spam placements. In this case, 5% of your delivered emails did not reach the recipients.With time, your spam rate could be increasing and preventing your mail from reaching your subscribers. For some senders, this could mean thousands in lost revenue.Thus, measuring your overall deliverability rate vs. Inbox placement rate before sending out the real email campaign is important.For example, a GlockApps test report will show you Inbox placements and spam placements of your email with major ISPs just within minutes, and calculate your Inbox rate and spam rate. Based on the report data, you can see how your message is treated and take steps to fix deliverability issues if detected.

      Plus, using GlockApps, you can verify your sender authentication such as DKIM and SPF, run the email against spam filters, and check your sending IP against blacklists.

      Email spam testing report from G-Lock Apps
      How ISPs Gamble with Your Reputation

    8. Provide a simple way to unsubscribe.It helps eliminate negative user feedback.

And the last but very important thing

  1. Ask yourself what your angle is.Is it a high rate of conversion or is it a high rate of deliverability? Do you really have to send the number of emails that you are sending to get that kind of conversion?If it’s about conversion, make sure your recipients actually like and engage with your emails. You might achieve higher conversion with fewer emails by sending, for example, 2-3 killing emails they can’t ignore instead of sending a dozen of vapid messages.

Here is to your success in email marketing!

Learn More:
Email Deliverability Ultimate Guide
How to Write Emails that Convert

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Julia Gulevich is an email marketing expert and customer support professional at Geminds LLC with more than 15 years of experience. Author of numerous blog posts, publications, and articles about email marketing and deliverability.