Email deliverability and spam filtering work like blowing up a balloon, if you blow to hard it bursts, the email is spam. Many individual issues contribute a puff of air into the balloon.
Some, such as spam complaints, give a bigger puff of air than others. Once the amount of air reaches a critical point, the balloon bursts and the email goes to spam rather than the inbox.
Just as for a real balloon, no one particular puff is responsible for bursting the balloon and no single puff will cause the balloon to burst, it is the sum of all puffs that’s important.
Seven things that blow up your email deliverability balloon
The key items that cause a puff air into your balloon and poor email deliverability are, in order of importance:
- Data source and collection practice
- Poor bounce management
- Poor complaint feedback loop management
- Content issues
- Poor data management
- Infrequent emailing
- Lack of authentication (SPF, DKIM)
This is a list of things that most likely cause problems, not a list of all factors that go into spam filtering and ISP reputation calculation.
The number one point is data source and data collection practice. This is because how the recipient sees you and their state of relationship with you has a big impact on their behaviour and whether they hit the spam button or read your email. Good data drives good user engagement, good user engagement drives great email deliverability and inbox placement.
Consider how customers got onto your list. Should someone provide their email address for, say, a quote, and not be clear they will also get marketing too, it will cause spam complaints. Purchased data will be much worse, not only causing high complaints, but high bounce rates and spam traps.
Authentication (SPF, DKIM) is listed seventh above as excellent data and user engagement is key. However, as SPF and DKIM are straightforward technical setup items there is no reason not to have these in place and in reality are must do items. All good ESPs have support for SPF and DKIM.
Data over content
So the first place to look when email delivery is a challenge is your data, not your content or sending infrastructure.
Consider these important data questions:
- Where did your data come from? From organic sign ups, competitions, purchases?
- How was expectation set in terms of how the address would be used and what would be sent?
- Has any old data been reintroduced?
- Has data always been well managed?
- Has unsubscribed data been accidentally re-introduced?
- Has the unsubscribe process stopped working?
- Has purchased data been used at any point?
- Are hard and soft bounces being removed?
Keeping a record of data sources is not only good for marketing performance, but also for deliverability. If you need to purge data to improve deliverability, then removing the less active data from the most risky sources first is a good strategy.
If you have squeaky clean data and emails are expected by recipients, then your balloons should not burst. The other factors such as content can play a part, but typically only if your data is not in perfect order.