When sending campaigns to subscribers at the big ISPs, such as Gmail, Outlook or Yahoo, the delivery parameters are somewhat learnt from experience. Rather than describing everything about how they filter spam, the ISPs are somewhat ‘black-boxed’. Their obligation is to their account holders, so it’s in their interest to ensure their practices are kept as confidential as possible in order to prevent spammers taking advantage.

Yet your chosen ESP should have enough experience of sending mail to pick up on patterns of what can help or harm, and advise you accordingly. You should also expect your ESP to be actively participating in the email community where the major vendors collaborate, trying to work with the ISPs as much as possible to ensure a positive experience for email recipients.

The result of this research and collaboration is a set of best practice recommendations for optimisation that can have a major impact on campaign criteria – affecting timing, size and which datasets to focus on – all with the one goal of getting mail into the inbox. 

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Minimise spam complaints

Deliverability can be viewed as both a science and an art. And using an ESP that cares about deliverability means they can be sympathetic to both viewpoints.

On the science side, your ESP should put as much science behind their delivery recommendations as possible, and strongly focus clients on metrics and best practice. But in this venue where data and algorithms are constantly changing, there’s no substitute for tapping into the ESPs’ experience, and using their relationships with the ISP networks. That’s where the art comes in.

On the science side, it’s been well established that sending to a lot of dead addresses (i.e. with permanent delivery problems) is obviously a bad thing, as it indicates you are using old data and the receiving network may flag it (rightly) as a trait of bad senders. To avoid this scenario, it is important to focus on spam complaint metrics, with the aim of minimising such complaints.

When recipients mark something as spam, ISPs have a system whereby they can provide records or spam complaint rates. While it’s important that today’s marketers don’t get so focused on metrics they lose sight of the bigger strategy, it’s also critical to investigate as many data-points as you can to improve email deliverability. 

Changing algorithms

Yahoo/Gmail/Outlook etc. work on a timeline that serves their account holders first, which means their update cycles reflect a world where they must update and patch their receiving protocols continuously in order to stay ahead of spam and security issues.

It’s important for marketers to grasp that rather than an update cycle based over months, where a fix-and-forget deliverability approach could potentially work, the ISPs’ spam filters are run by algorithms, so they can change second-by-second. This means that ensuring campaigns are delivered is an ongoing process of monitoring and adjusting variables. This is where the “art” component comes in.

Consider this example: on day one of a new campaign the open rate was 30%, the complaint rate 1% and the bad address rate was 0.1%. The next day the metrics were even better, but the campaign got blocked on the third day. In this scenario, it’s obvious that deliverability metrics alone cannot give you the whole picture, highlighting the need for a productive partnership between ISP, ESP and marketer.

If your ESP has a productive relationship with the ISP, they can put in a call, and the ISPs will often share some level of data with trusted sender networks (of which Adestra is one), but for security’s sake no ISP is going to share all its data with anyone. 

One campaign doesn’t make a delivery trend

If a brand is getting email campaigns blocked at a significant level (if, for example, you are sending to two million people a month nothing will prevent you being blocked somewhere) – then it’s important to look at the broader picture from an ISP point of view. You might get blocked one day, not the next, and then you get blocked again, so there is clearly some kind of a linked sporadic issue. In other words, there is something in the nature of your list or content that puts you in the ‘spotlight’, that the ISPs look at. For reasons that ESPs and marketers may never know 100%, the ISP has interpreted something is going on with this sender, and they may be teetering on the line between ‘a risky or a less risky sender’. 

Deliverability is a very ‘lenient’ science and, if clients focus only on single campaigns, without the benefit of the bigger picture that only the ISPs will ever see, the decision on whether to block a campaign or not can appear contradictory. That is why we try to focus not on a single campaign, or day-on-day activity, but the trend over time.

If you are having continued issues over time, then there is definitely something to investigate. 

Working with the ISPs 

All ISPs operate logically, in the most literal sense of the word: they follow algorithms and elaborate rules to evaluate whether or not a message is legitimate. They’re very robust systems, but they can only ever be as good as the formulae put into them.

When threat researchers are trying to thwart spammers who are trying just as hard to come up with the next clever hack, both parties are making the best guesses possible, but they’re still guesses. That’s the part where an ESP has to review all the data and look at how it perceives each ISP works. If an ESP has a good relationship with an ISP, and thinks they’ve made a mistake, then it can sometimes attempt to explain why. 

The dynamic between email account holders, the ISPs, and nefarious players is an important one to understand. You’ll notice that nowhere in this equation is the ESP or marketer. In a deliverability world the ESP or client doesn’t have a business contract with Yahoo, Outlook, or Gmail. They don’t have to receive our calls, they don’t have a timeframe within which they must reply to us, in fact they could ignore us. 

An ESP has to go to a trusted contact and put the case forward as to why it thinks this client is not being treated fairly with supportive evidence. They will consider qualitative and quantitative factors such as: do the representatives from this ESP complain to us every single day no matter how the client is performing? Or have they actually done their homework? If an ESP has acted in good faith, and their complaint is justified, the ISP engineering team is much more likely to review the case. 

It’s sometimes difficult for clients to accept that ISPs operate solely for their own customers, rather than the world of promotional email. Nobody at an ESP or client sender can demand an answer within the hour or expect to talk to someone’s boss or their boss’ boss at the ISP, that’s just not the way it works. 

Even given all the tech being utilised on both sides with algorithms, automation, metrics and so on, it’s still a people business. Don’t forget that the personal relationships with ISPs are not commercial – otherwise, spammers would simply buy in too! – they are however a means to improve deliverability for both senders and receivers of legitimate email.

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Econsultancy also offers email marketing training.