No one likes a complainer. Particularly when it comes to email marketing. However, complaints happen – even to the best senders – and receiving a complaint doesn’t necessarily have to be doomsday. Actually, the email complaint rate can be an extremely helpful indicator revealing any blind spots in your email program as well as help you optimise your email processes and increase subscriber engagement and ROI.

“A complaining customer can be your best opportunity to show how good you are… and create a customer evangelist.” – Shep Hyken

The assumption that if you are a ‘good’ marketer and only sending to permission-based email lists you are safe from spam complaints is ludicrous. Each and every subscriber can report or complain about marketing emails they don’t like. It could be the result of content they don’t deem particularly interesting, the fact you email them way too often or they just might’ve lost interest in your brand in general. Whatever the reason, it’s crucial for businesses to have a better understanding of their email complaint rate (a.k.a spam complaint rate) and how it can be harmful not only to your sender reputation but also to overall email deliverability.

In this article, we’ll cover the following topics on email complaint rates:

  1. What is an email complaint rate?
  2. What prompts subscribers to complain?
  3. How to reduce your complaint rate?

Let’s dive in.

As email marketers, you certainly know that even if subscribers don’t communicate back by replying to your marketing emails, they have various other ways to engage – opens, clicks, marking your email as spam, complaints and whitelisting. All these actions can affect your email deliverability. The way subscribers interact with your marketing emails is a determining factor of whether your message will end up in the Inbox or the Spam folder.

TiNS, TiS and Email Complaint Rate

Have you heard of TiNS? What about TiS? Spam complaint rate? As email marketers, we’re certain you know what we’re talking about. However, for those that might be new to the email marketing world – or might’ve forgotten, let us explain.

What Is TiNS?

According to Return Path, TiNS is an acronym that refers to the phrase “This is Not Spam”. It’s often used to represent a non-complaint – a spam folder placement false positive. TiNS data is registered by ISPs when a recipient marks an email already placed in their Spam folder as “not spam”. To put it simply, TiNS is the ‘thumbs up’ ISPs give to the senders’ email messages.

What Is TiS?

As specified by Return Path, TiS is an acronym that refers to the phrase “This is Spam”. It represents a spam complaint. By using the TiS button recipients express their displeasure about receiving abusive or unwanted marketing emails. It’s important to note that despite some ISPs attempting to submit unsubscribe requests on behalf of their users in addition to the user reporting the email as spam, it doesn’t mean the user will be automatically opted-out from the sender’s email list. Simply put, TiS is the ‘thumbs down’ ISPs give to the senders’ marketing emails.

Now that we’ve cleared up those terms, we’d like to focus on email complaint rates (also known as the spam complaint rate).

What is the email complaint and spam complaint rate?

Email complaints (also referred to as abuse complaints) are a direct signal recipients give to mailbox providers (ex. Gmail, Yahoo!, Outlook, Hotmail, etc.) that the email they’ve received is unwanted. They occur when a recipient clicks on the TiS button in their email client. If the ISP has a feedback loop (FBL) in place with the ESP, the latter will be notified of the recipient’s action.

An email complaint rate represents the number of recipients who reported your email as spam divided by the total number of email you’ve sent.

Number of Complaints / Number of Emails Sent = SpamComplaint Rate

Ex. 5/5,000 = 0.1% complaint rate

However, the above formula will not necessarily give you an accurate idea of the complaint rate ISPs are observing. This is due to the fact that not all ISPs have feedback loops set up with ESPs. The following formula will help you calculate your complaint rate per ISP or domain (ex. – 

Number of Complaints from Gmail / Number of Emails Sent to Gmail = Gmail Complaint Rate

An email complaint lower than 0.1% (1 complaint for every 1,000 emails sent) is considered to be acceptable – and industry standard. Any percentage above 0.1 is considered high and may affect not only your email deliverability but also result in your account being suspended by the ESPs.

It’s crucial to be vigilant about your email complaint rate. Not only because it’ll affect your email deliverability, but because it can also impact other users on the same ESP platform. If ESPs register high complaint rates it can damage not only the overall relationship they have with ISPs but also, the reputation of the sending IPs.

What Provokes Subscribers To Click The TiS Button?

Email marketers are often quite surprised when they see a high email complaint rate – “Everyone on my email list has opted-in to receive my emails. I’m not sending spam. Why is this happening?”  However, complaints can happen at any point in the subscriber journey and for a variety of reasons. No one is 100% safe – even marketers who’ve never spammed anyone.

A few key reasons why subscribers might mark your emails as spam – 

a) recipients didn’t consent to receive your marketing emails;

b) a person who doesn’t differentiate .com” from “” – or simply made a typing mistake – singed up and the address is valid, however, the real owner of the email address hasn’t opted-in and so it results in a spam complaint;

c) the person opted-in to receive your email messages, however, once they get an email it doesn’t generate recognition and thus leading to a spam complaint;

d) your company has been acquired by another or you changed your ESPs or re-branded – if you didn’t notify your subscribers, the next time they get an email from you they fail to recognise it and therefore, mark it as spam;

e) your email messages are too infrequent or, exactly the opposite, you send one too many and way too often – the inconsistency and lack of presence in the subscribers’ inbox could be detrimental to your complaint rate. Contrarily, sending too often can be annoying. Both may result in the recipient either hitting the TiS button or unsubscribing altogether;

f) your emails look like spam or someone is spoofing your sender domain – email fraud has put everyone on edge and if your subscribers detect even the slightest indication your email message could be a phishing attack they will immediately stop trusting you and hit the TiS button;

g) companies are not sending the content subscribers thought they opted-in for – If a subscriber signed up for your newsletter but is getting tons of promotional emails and offers instead they will unsubscribe or worse, mark you as a spammer;

h) you’ve made it difficult for subscribers to unsubscribe from your correspondence;

i) your emails are not responsive and load very slow; and

j) your recipient just got lazy and clicked spam instead of unsubscribing.

Reducing The Spam Complaint Rate: Best Practice

Is your email complaint rate higher than the industry standard – 0.1%? If it is, this best practice list will guide you through the process of avoiding future spam complaints.

1) never use purchased, rented or borrowed email lists – they are not permission-based and can contain spam traps. Also, the people on those lists didn’t opt-in for your emails;

2) do not signup people automatically – if they wanted to be on your email list, they would’ve opted-in themselves;

3) only email contacts who’ve explicitly opted-in (preferably in the last 12 months);

4) use double opt-in – it’ll help you prevent fake signups and ensures only valid email addresses – of people who actually want to receive your emails – are added to your email list(s);

5) send a welcome/onboarding message after contacts have signed up – it’ll allow them to familiarise themselves with the look and feel of your brand & whitelist your ‘From address’ (if you ask nicely);

6) ensure the subject line is clear –  your subscribers should know what your emails are about from the get-go;

7) make it easy for recipients to unsubscribe – it’s better to lose a subscriber or two than to have your emails reported as spam. The first will not harm your deliverability, the latter will;

8) create a custom domain (if you don’t already have one) – if your marketing emails are coming from the same domain subscribers signed up to they’ll recognise it and you won’t have to fear being reported as a spammer;

9) make sure you always send relevant, personalised content – if you bombard your subscribers with promotional emails and offers all the time, you’re basically ‘begging’ them to complain; and

10) be vigilant about the email frequency – you neither want to send so few emails your subscribers forget they even signed up (or who you are) nor do you want to overwhelm them.

Final Thoughts

First and foremost, remember that a high email complaint rate can – and most probably will – result in long-term deliverability issues. These can take several months to correct and get your sender reputation back on track.

Secondly, email marketing is not a one-way communication channel, it’s a two-way street. Your subscribers always have a way to respond to your marketing emails be it through opens, clicks, unsubscribes or spam complaints. Thus, it’s imperative to pay close attention to what they are saying through their actions. This way, you’ll have the opportunity to improve any weak points in your email marketing program. As well as your overall email deliverability.

Finally, once you’ve incorporated the proposed best practice, you’ll definitely start seeing results. They will help you to not only build a better relationship with your subscribers but also, increase your ROI.

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