Simplifying Common Email Deliverability Terms

HubSpot Employee

I am a Technical Consultant on the EMEA Professional Services Team and one of my specialities is Email Deliverability.  I am frequently brought into situations where customers are having issues with their email sends to assist them.  I liken email deliverability to SEO - everybody has a general idea of what is definitely important, opinions about what could be impacting it and some tricks but in reality, the algorithms change every day and each user has a completely different experience.  The exact same can be said for email deliverability.  In this post, I will be taking some common functionalities associated with email deliverability and explaining on a SUPER high level (and honestly a bit strange) what the functionalities mean. Buckle up for the weird....


Email deliverability is two-fold.  It is gaining access into the mailbox and also placement in the inbox.


Take a moment to think about email providers as nightclubs.  You have the really strict, asks for three different forms of ID, over 30's nightclub.  There is the standard over 21's nightclub that you have to be wearing good shoes and no tracksuits allowed.  Finally, there is the dodgy, everyone is underage, wearing tracksuits and runners nightclub. Each of the nightclubs has different rules and criteria you need to meet in order to get in. 




This is the same for email providers; if you meet their particular rules and you have a good reputation you will get into their nightclub (mailbox).  These rules can change dependent on management decisions, that can change at any time.


If you have an amazing reputation and are 'known' as a big deal that everyone wants to talk to, then you will not only get into their nightclub (mailbox) but you will also get into their VIP area (the inbox rather than spam/trash etc).


There are different email authentication methods, for example, SPF, DKIM, and DMARC.  Think about these as different kinds of ID’s.  Some night clubs will be more likely to let you in when you show a particular ID, others won’t even ask for it. 




Think about hen (bachelorette) parties.  One Saturday night, there are two women, Mary and Sarah, on their hen parties.  Mary and Sarah are out with their own group of friends both of whom have 25 friends and they are all dressed up that make it clear they are a hen party!  Both groups want to get into the 'in' nightclub.  Mary and all her friends get up to the bouncer, Michael, and are told that they don't allow hen parties into the nightclub and the group are not allowed in.  Afterwards, on the same night, Sarah and her friends arrive.  Michael knows Sarah really well as she is a regular to the nightclub.  He knows she won't cause trouble so he lets her and all of her friends in no problem.


This is what happens with throttling - too many emails from one source arrive at the email provider at one time and the 'bouncer' is saying 'we don't know you and you don't have a reputation here so you aren't getting in'.


Mary and her friends have another hen party the following week and they want to get into the same nightclub but they have learned they won't get in all at the same time.  This time they are going in separately and once they get in they are on a mission to engage with the staff and get a really good reputation so that for the next hen party they won't have to segment their party group.




If someone rejects your advances in a nightclub, don’t keep hounding them until they get you kicked out (maybe forever?) #dontbeajoe




The change in email deliverability when you move to a new marketing email sending platform (ESP)

When you move to a new ESP, you may see a decrease in engagement initially.  Some members of the Email Deliverability Jedi Council**, gave me a go-to analogy of this process.  Imagine the email sender is the new girl at school. She was cool at her old school (old ESP) and everybody let her sit at their lunch tables (contacts' email inbox providers). Now she's at a new school (new ESP) and while she's still cool and has a great personality, people need to warm up to her and she needs to build a good reputation. 


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It can also happen that sometimes you could move to a new ESP and see an increase in engagement and this can happen for a number of reasons which I’m not going to delve into today but be aware that unless you adopt a good reputation you will eventually be impacted.



A Spam Trap is actually defined as a ‘honey pot’.  Purchasing lists, scraping emails from the internet, using old contacts that you haven’t spoken to in years, using dubious software that will ‘promise you all the leads you could ever want’ etc are the honey pots you need to look out for.  The data looks good and very tempting to send an email to however if you give in and one of those contacts has been marked as a spam trap/honey pot, then you will get marked as having spam practices and potentially blocklisted meaning no more emailing anyone on that ISP (Internet Service Provider).


ISP’s are actively putting their ‘honey pots’ out into the internet cloud to try and lure those that have bad practices in.  



Some customers of mine will add contacts that they haven’t heard from in over 10 years into their marketing list and wonder why they got blocklisted - ‘This person exists, this is their email... I worked with them years ago’.  


This could be a “double-agent” (honey pot/spam trap), sometimes if a person leaves a company after a reasonable amount of time has passed this email address will be marked as a spam trap as it can be assumed that anyone email an inactive account after X period of time is not getting this email address from the contact.  So to avoid spam traps?  Don’t email people that don’t expect to hear from you.  Don’t email people that you haven’t heard from or interacted with recently.


Your mission: Eliminate bad emails…. 



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I hope that you found this helpful at the beginning of your journey through all of the email deliverability nuances.  


** Email deliverability Jedi Council members Apollonia, David and Lauren.

3 Replies 3
HubSpot Employee

What an amazing post! Really comprehensive and great tips that can be applied to improve email deliverability. 


@kaburke I recently realised my normal email were being spammed quite a bit (even to contacts I had already emailed / had email conversations with)! But after a lot of faffing about, I realised it wasn't a problem with the above... but rather it was a problem with using your free email signiture generator.   (Which is annoying as it made my emails look great!)


Basically it turned out that the images / links / html had been hashed in something called razor (which spam filters aparently use) and as soon as I removed the footer my emails stopped being spammed and my score on went from a 5.2 to a 9.3!

Maybe worth looking into if there is a way to stop this from happening?!



HubSpot Employee

Hi @michael-e-howe !  This article is about marketing emails rather than sales emails which I think may be what you are talking about?  I can't say that I have heard about this before, do you have a support ticket number that I could take a looksie at?