Email Deliverability

I’m going to give you an insightful look into how to achieve good deliverability

3 Pillars of Deliverability

  • Infrastructure
  • Reputation
  • Authentication

If you did not know, 1 in 5 emails don’t get placed in the right mailbox, that’s 20% of your emails sent don’t ever make it to someone’s mailbox because you might be not (willingly or unwillingly), complying with the best practices and rules of deliverability. Respect the rules, get higher deliverability!

It’s that simple

70% of emails sent worldwide are spam!

So let’s start with…


  • Respect the HTML format, don’t add unsupported HTML features or JS
  • Let people unsubscribe nicely or update their receiving
  • Ease up sending when you get started, and stay consistent
  • Follow on complaints (spam/flagging), minimize them ( < 0.1% of your total send list)
  • Don’t fall for honey pots — don’t use crawlers to harvest emails, don’t use other people’s email lists (or at LEAST, don’t acquire them from people you can’t trust)
  • Monitor bounce rates (soft bounce = out of the office/unavailable inbox could be full or suspended, hard bounce = email address unreachable/invalid)
    — Use opt-in or double-opt in processes
  • Segment email address of people who are active and prefer them over those who are not active. ( this is also called list filtering)
  • Don’t use no-reply@yourcompany…it’s a bad practice to not monitor replies
  • Include plain-text emails, for a whole bunch of reasons


Dedicated and warmed up IP addresses for new senders — otherwise you will be sharing the reputation belonging to the previous sender on that IP
Secure server infrastructure from malicious users who might use your platform to spam or do other funny business
ISP feedback loops — use them to know what’s going on when people hit report/spam emails (M3AAWG)- most people use ReturnPath’s service but there are some companies who use their own services (i.e. GMail)
Make sure you have your own abuse (postmaster@, abuse@) set up on your own mailservers
Collaborate with spam filters like Barracuda or IP2BAN, and be aware of 3rd party hosted filters like CloudMark, MessageLabs
Rate Limits


Just read my other article to secure your emails and fight Unsolicited Bulk Email (UBE)
What Is Email Authenticity — Email Marketing secrets
This basically gives you an overview of:
How can you lessen the risk of your messages ending up in a spam folder using SPF, SenderID, DKIM, Domain Keys…

Feedback Loops (FBLs)- AKA know when things go wrong

Good things to know before getting your hands dirty into FBLs.

  • You must own the IP/domain, or have admin rights, in order to register for a FBL
  • There must be a working abuse@ or postmaster@ email address for your domain
  • The rDNS of an IP being entered needs to match the domain being used
  • Most ISPs specify that a good reputation is needed to be accepted on their FBL

Super good resource to keep in mind when getting started with FBLs

Your good or bad reputation can be checked on:

  • Barracuda Central

Avoid being BlackListed at all costs, always check on:

Staying clear from these lists is a must!

These help mostly combat spammers by letting you know when an email sent from one of the mail servers hosted by your service has done something naughty.

Yourself or your users can be categorized as one of these three groups:

  • Spammers: These individuals knowingly violated terms of service and sent spam intentionally.
  • Aggressive marketers: Individuals who are abusing email by acting aggressively or without the respect of the end user (legitimately)
  • Victims: Someone whose email account has been compromised and used by spammers

Block spammers, educated marketers, help victims

Until next time!