To maximise ROI from email campaigns, marketers need to monitor delivery, and take action to maintain good inbox delivery rates. 

Here are 15 valuable tips for monitoring and improving email deliverability, taken from our Email Marketing Best Practice Guide.

The diagram below, from dotMailer, shows the path of a marketing email, as it goes to the intended recipient's inbox, is filtered into the junk filter, or bounced back by the ISP: 

Pre-broadcast review for spam characteristics

Check for use of spam keywords and other spam characteristics in emails

For each campaign there should be a process to check the spam score for emails to see that your email doesn't exceed the threshold.

Here's an example of a spam report: 

Don't use IP address for links.

You shouldn't use an IP address in links to pages or images. It's unlikely you will, but worth mentioning, since it's what phishers and spammers often do.

For example, do not include a link as This will cause Outlook to disable the links and label it as spam.

Send emails to seed email accounts to check delivery

They should at least through your own firewall, Gmail, Hotmail, Yahoo! Mail. Additionally, use an inbox delivery tool checker before broadcast.

One or two addresses per ISP isn‘t going to give you the statistically valid data, you need at least 10 and sometimes more depending on the size of the ISP. 

Mail server and IP address reputation

Configure email server to authenticate quality

The setup of the broadcasting mail server is not generally the concern for marketers managing the campaign. But you should check that your email Service Provider or in-house broadcaster is using these techniques:

  • Setup physical address on sub-domain. The sub-domain of the main client sent is used for a physically separate broadcast service, e.g. :, for example: (This is not essential, but good practice).
  • A & MX records An „A‟ record is needed for click and open tracking. The „MX‟ record is for emailing. This setup is needed to verify sending IP address and for replies/bounces to be routed back to the server.
  • Setup Sender Policy Framework
  • Setup Yahoo! Domain Keys.

Act on emails reported as spam

Best practice is to setup a feedback loop system between the ISP / webmail provider and the broadcasting email service provider or in-house server and then emails reported as SPAM are removed from the list in the same way as if they are bounced.

This prevents repeated reporting of emails as spam.

Review the profile of people reporting your emails as spam

Look at the profile of the people reporting email as spam. For example, if they are recent subscribers, then it may be necessary to tweak the opt-in process, and make sure that it is clear what people are signing up for. 

Check for blacklisting

If you notice problems with your deliverability, check that you are not on a blacklist.

You can check using a service such as the Lashback Unsubscribe blacklistBlacklist Monitor or the free check available via Return Path Senderscore.

Consider impact of presence of emails in spam traps.

It is not usually possible to check for addresses in your list that are potentially causing problems in spam traps.

If an email in your list is discovered in a spam trap this can lead to a permanent block, so your are most likely to find this if your deliverability falls dramatically.

Remove inactive subscribers from list

Send an email to people who have neither opened nor clicked in the last year asking them to confirm they still want the email. Then you are less likely to be reported as SPAM and this is a potential way to remove emails in spam traps.

Regular cleaning of inactive addresses, which have not interacted within a 12 month period will help to prevent deliverability issues caused by emotionally unsubscribed recipients.

Consider sender warranted certification

In certification systems, the broadcaster signs up with a company, such as Return Path. Subscribers must adhere to strict rules around the reputation performance of their email and then they pay a licensing fee. 

You need a good reputation to be part of these schemes, they are not a way to simply pay and ignore reputation issues.

Prompt users to add you to their address book 

You should encourage recipients to add your address to their “Safe senders” list or address book, so that even if message has characteristics of spam it is not placed in junk box.

Not many will do this, but it is still worthwhile since it can guarantee inbox delivery. Here's an example from Comet: 

Since the proportion of recipients who respond to this are so small, it is arguably more worthwhile to do this as part of a signup process or welcome campaign rather than including it as a standard template feature.

Add unsubscribe links and instructions

Every email should contain unsubscribe instructions by law, and you should carefully word your unsubscribe method so it doesn't look like that commonly used by spammers. 

Using a 'Statement of Origination' or explain with text like 'why am I receiving this email?'. Spammers often use fake statements of origination, so it's best to check the text against a filtering system before delivering the campaign.

Your statement of origination should explain either that the recipient has opted in, ideally with the place and time of opt-in, or that they are receiving it since they are an existing customer.

Placement of unsubscribe links is another important consideration. They are most commonly found at the bottom of emails, but there are some good arguments to make it easy to unsubscribe through prominent links, as with this example from Pizza Express. 

Provide visual reassurance that you are a trusted brand

Approaches include:

  • Ensuring the email branding is clear so that your company is identified.
  • That the email branding is the same as the branding the user would have seen at time of sign up.
  • Put your company name, address, registration number, contact details in the email footer. This is also a legal requirement in many countries, including all European countries.

Review deliverability for all campaigns

While most marketers will mainly be interested in opens, clicks and transactions when reviewing their campaign reports, you should always look at delivery also.

Compare each campaign to your past history of delivery percentage to see whether you have a problem and then act on it.

You should separately review inbox deliverability since an email may not bounce, but has been placed in the junk mail folder in which case it is less likely to be acted upon by the recipient.

Review inbox deliverability for web mail companies and major clients

You can tell whether you have an inbox delivery problem by comparing the relative delivery for different groups of recipients.

Better still, look at open and click rates for different groups of subscribers and this will give you an ideal of inbox delivery or rendering problems in a specific email client such as Hotmail.

Graham Charlton

Published 26 September, 2011 by Graham Charlton

Graham Charlton is editor in chief at SaleCycle, and former editor at Econsultancy. Follow him on Twitter or connect via Linkedin.

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Comments (11)

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Sean Duffy

Goodmail stopped existing ages ago:

Return Path are the only ones to offer a worthwhile Certification scheme nowadays.

Content filtering is fairly old hat, particularly the Spam Assassin filter shown above. This comes from the same thinking that using a particular colour will get your email blocked - nonsense. Of the content filters that still are important Spam Assassin does not give a good indicator of likely problems - much better to send to a seed list offered by nearly every ESP of real mailboxes.

Outlook is the one remaining problem content filter - we know the good and bad words it looks at and have a nifty tip to get around this one - email me if you want to know more ( - we don't publish this tip as we don't want spammers using it!).

Content filtering (in most but not all cases) is used if you have a dodgy reputation - its too costly for an ISP to process every message through processor hungry filters.

Also number one factor is missed off the list here - send relevant, valuable emails. If you do this then you are unlikely to have any delivery issues long term. It is also not a bad thing to aim for anyway!

almost 7 years ago


Adam Sewell

Most of these are good reasons for using an established ESP rather than trying to manage bulk email sending yourself.

almost 7 years ago


Craig Swerdloff


Thanks for the thorough advice. Would you consider a follow-up post on 15 Best Practices for collecting new data to improve email deliverability? If so, let me know how I can contribute. Through LeadSpend's real-time email validation service we see a lot of market data on what works and what does now.

almost 7 years ago

Graham Charlton

Graham Charlton, Editor in Chief at SaleCycle

@Sean Thanks, have updated now. That particular tip came from our Email Best Practice Guide, which was published just before Goodmail's demise.

Sending relevant, valuable emails is of course the most important factor, perhaps so obvious that I left it off the list.

The assumption here is that you have that part of the campaign sorted out already, and these tips should help you to deliver those relevant emails...

almost 7 years ago



The infographic is a bit deceiving - having accreditation/certification doesn't mean your email will be placed straight into inbox - ISPs still have to apply their behavioral rules on top of that.

almost 7 years ago


Sean Duffy

Graham - Indeed it is obvious, and most marketers know that but still ignore that in the goal of whacking out another set of offers cheaply and quickly...

Alec - Certification doesn't mean you are guaranteed but at Yahoo and Hotmail it might as well be. Very unlikely to have any issues at all if Certified with these providers. For the cost vs benefits definitely worth doing

almost 7 years ago

Graham Charlton

Graham Charlton, Editor in Chief at SaleCycle

@Sean I'd agree with that, there are still plenty of email marketers that perhaps need to learn the basics first.

Sorry about our spam filter btw, I've had to manually approve your comments, which explains the delay.

almost 7 years ago



Spam is so bad now even legitimate email end up in the spam can. I think they should update mail() so that every email it processes writes to a log file recording the domain and URL page that sent it. Since many web masters don't even know they have a problem

almost 6 years ago


John Smith

Great tips because when you submit email so many email goes is spam. after using of these tips we can send email to user inbox.

over 5 years ago


Jay Perez, DB Manager at GSC Ltd

Excellent checklist Graham! I would add up another tip which to me is the "corner stone" to create a solid foundation to get a consistent email deliverability rate: I'm referring to the email list validation. As a DB manager I've learned a while ago that since this is a very specialized task, it should be left to the experts. After testing different services, we tried and we can't be happier... We rely 100% on them, we just upload the files and they take care of all the rest. Fast turn over, affordable rates and customer service second to none... Once I get the lists all scrubbed is when we follow point by point a protocol pretty similar to the one your listed right here in your article. Kudos to you as you presented it quite clear and easy to follow

about 5 years ago


Erin M, Manager at SendinBlue

My team (at SendinBlue) works hard to help email marketers optimize deliverability for marketing campaigns, automation, transactional emails.

We've found that an email sender's reputation with ISPs is one of the most key elements to reaching the inbox. Your tips are a great starting point to building a positive reputation.

These 3 factors are actually the most important for understanding and improving your sending reputation:

1. Email history with your contacts

2. Your domain’s sending reputation

3. Other questions, such as:

- What IP address are your emails sending from?
- What content is in your email? Is it relevant to your contacts?
- Have you been reported in a blacklist?

This post on MarketingProfs gives a clear, easy to follow overview of how email deliverability works:

about 2 years ago

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