Internet Performance Delivered right to your inbox

Two Common Email Delivery Mistakes That Cause Unnecessary Hard Bounces And Complaints

(This post originally appeared on, where you can read original monthly posts from this author and plenty more.)

In my years of deliverability, I’ve seen a lot of mistakes made – many of which are talked about on this site. No matter how bad an error and how many experts try to teach the masses not to do it again, they still manage to keep happening.

With regard to hard bounces and spam complaints, here are two I come into contact with a lot. Seen these before?

Email Cadence

This is when a sender delivers multiple emails one right after another without giving any time for the receiver to a) validate what they’re getting and b) take an action if they see an issue.EmailDelivery

If a user is going to complain about an email, they need a chance to opt out and get on your suppression list before they are sent another email. If you send out an activation email and a welcome email, have the welcome email be a trigger off clicking the activation link rather than an immediate send when they get on your list.

This way, if the email address bounces or the user complains, you have only sent one email to a bad location and not multiples.

I often see companies that send user-to-user emails or update emails (think social network updates) way too often. The problem is that sometimes, even multiple emails per day have higher than necessary complaint rates because senders refuse to send a single email with all updates or user communications for the day. The end user gets exhausted by the amount of email from one source and thus, they get upset and complain.

Sending To Address Books

Another strategy that inflates hard bounces and complaints is applications that allow you to send an email to entire address books within email systems like Gmail, Hotmail, etc. You’ve seen this before: rather than selecting individual contacts in a given address book, users simply give permission for the application to send to everyone.

While that initially might seem okay (I mean, you do know who owns every single email address in your book, right?), it can actually cause more harm than good.

A problem is this method will sometimes send email to addresses like postmasters@ and abuse@ that the user previously corresponded with for an email issue. Also, the majority of contacts being sent to don’t know the brand and have not subscribed to receive these emails – another way this causes complaints. Old email addresses in the users’ contact lists cause hard bounces.

All of this combined can have a very detrimental affect on your reputation.


Allow an appropriate amount of time for your suppression list to be useful and think about making your send-to-address book functionality more sender reputation friendly.

Share Now

Whois: Stephen Wheeler

Stephen Wheeler is a employee at Oracle Dyn Global Business Unit, a pioneer in managed DNS and a leader in cloud-based infrastructure that connects users with digital content and experiences across a global internet.