How To Improve Your Email Deliverability And Avoid SPAM Filters

Posted 22nd April 2020
By Dawn Saltmer

In order to gain more engagement in these challenging times, businesses are ramping up their marketing communication efforts and reaching out to their database communities. As consumers and customers, we all appreciate that algorithms and filters are essential to stop our inboxes being flooded with unsolicited emails, however, as a sender you need to be aware of the rules and requirements in order to prevent your genuine email being written off by the algorithms as spam. Here are some helpful suggestions for you to consider:

Email reputation

There is a scoring system put in place from the big email giants such as GMail, Outlook, Yahoo etc., to measure email reputation. It is measuring how much of a “threat” you are to spamming people. This score is made up of the following factors: 

  • Complaints
  • Blacklists
  • How much you are sending
  • Spam traps

Complaints by far are the biggest factor which may negatively affect the reputation score.

Where the email is coming from

If you are using a reputable marketing tool, such as Infusionsoft, Zymplify, Mailchimp, Hubspot etc. these companies will be monitoring emails closely, as they also have a reputation to upkeep. They will be looking/checking to make sure they are in good health, that people using them are not doing any damage, and if they are, move them onto a lower grade IP so it doesn’t affect everyone else. 

They will constantly be checking:

  • IP addresses
  • Domains
  • Authentication


Each email content is scanned by spam filters. Alongside looking at the subject line, the filtering algorithm is also taking into the account the following:

  • Image to text ratio – we recommend having no more than 2 images in an email. If you’re sending a newsletter for example, send a plainish email, with a link to your hosted PDF newsletter or to blogs/articles on your website. Pretty emails do not out-perform text-based emails, although the law of attraction in marketing requires brand communication to be eye-catching and engaging.
  • URLs – it will look at the domain of any urls within the email. These URL’s must not be on any blacklists. So if you url points to www.unbounce, then unbounce must not be on any blacklists.
  • Attachments – keep them to a reasonable size. They could be too big for some providers to receive and they could be seen as a virus spreading tool. 
  • Fonts and colours – stick to standard, simple fonts and colours. Anything unusual might not only complicate email deliverability, but also increase the risk of unusual fonts not to be rendered properly at the receiving end.
  • HTML code needs to be clear and well written
  • Spam words – If you can, avoid using the below in your email content
    • Offer, promotion
    • Guarantee, promise, risk-free
    • Winner, congratulations, 
    • Avoid using phrases including the word money or variations £, $ etc.
    • Avoid words and phrases about it being free
    • And definitely not “This is not SPAM”
       If in doubt, use a spam checker tool such as, or Litmus


Audience, and particularly the engagement of your audience, is key. Emailing people who are not engaging with your emails will damage your reputation.

  • Be targeted
    • Gather information about your database, and talk to them about what they are interested in. If they filled a form out on your website saying they love cats, send them emails about cats. They may also like dogs, but they asked for info about cats specifically, so sending something about dogs may get them reaching for the spam button. (although who doesn’t love a puppy picture…)
  • Keep your database clean
    • You may have email addresses in your database that have come from bots filling in your webforms. Remove these email addresses as they could be spam traps and will almost certainly damage your domain.
    • Take notice of your out of office replies. Don’t just delete them, these contain valuable information. Such as someone has moved jobs, left the company or retired. If you carry on emailing an abandoned email address, this will count against you in the spam scoring.
  • Allow people to opt-out
    • Having an unsubscribe button may seem detrimental. Surely you don’t want to give people the option to stop hearing from you? The answer is YES. If the option to choose is not provided, your recipients could report you as spam which is damaging to your spam score. Besides, if they don’t want to hear from you, why keep emailing them? Respect their choice and concentrate on the people that are interested in what you have to say.

Quick tips to optimise your email deliverability:

  • Keep your brand consistent and recognisable. You don’t want people reporting your email as spam simply because they did not remember you.
  • Don’t use misleading subject lines. If people feel tricked into opening, they may feel more inclined to report your email as spam.
  • Warm-up your IP. If your email marketing system is new, or you haven’t utilised it for a prolonged period of time, it is advisable to “warm up” your database before committing to an intense email activity. Follow the advice given by the particular system you are using. While it might be tempting to send the first email to your entire database, it’s a good idea to stage the delivery to avoid starting on a bad foot with the scoring system.
  • Pick the best time. Studies have shown that the best day for email dispatch is Tuesday, and the best times are 10am, or 3-4pm. While it is important to take the advice on board, you should consider doing some A/B testing to check whether this is true with your specific audience.
  • Keep it regular and commit to consistent email communication. Sending one email per month might not be helping with the overall engagement of your database audience, therefore strategise upfront, establish communication themes and stick to the new routine of email communication.

Focus7’s CRM and business automation experts are always happy to advise you on the best practice and industry advice. Give us a call on 01462 262362 or email us at to start a conversation. 

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