Email Marketing

What affects email deliverability and success of email marketing campaigns most?

Email marketing is not only the most cost-effective way of marketing but it also provides maximum ROI (Return on Investment). Businesses including brands using email marketing in one way or another to reach out to their customers. Since the biggest advantage of email marketing is cost-effectiveness, it is a boon for small and medium size industries. Today everyone has started using email marketing for communication with clients and this has created problems for the end recipients that get hundreds of emails in their inboxes regularly.

How do recipients react to bulk mails?

  • Emails are deleted after reading the subject line
  • Recipients start unsubscribe from the mailing service
  • The worst thing is to report the mailers as spammers

To solve the issue, Internet Service Providers (ISP) don’t allow the emails to directly hit an inbox. Different levels are created for emails. Gmail has social and promotional for marketing mails and Yahoo has Spam/Junk folders for such messages. But most recipients are unaware of such folders hence they check their inboxes only. Others check Spam folder but only to delete the messages.

It is for this reason that email deliverability is the first step towards a successful email marketing campaign. All other factors like content, design and offer come after the deliverability.

There could be many factors that determine deliverability of an email but there are only 4 major factors that have major impact on deliverability of emails

  1. Bounce – soft bounce and hard bounce

It is a term used at server level and it denotes rejection of emails by server. It is further divided into soft bounce and hard bounce.

Soft bounce: When a mail is rejected due to its size or the mailbox, where the mail is directed to, is full or server issue which happens in rare cases, it is called soft bounce. The sender SMTP (Simple Mail Transfer Protocol) resends the bounced mail three times before giving up with failed delivery message.

Hard bounce: When a mailing address or the domain name is wrong, the mail bounces back and it is called a hard bounce. Here SMTP doesn’t resending the mail.

  1. Reputation check

Mails that pass through SMTP successfully have to undergo more checks before they are finally delivered to their respective mail addresses

  • Track record: IP addresses are tracked to check their record of sending bulk mails
  • Spam complaints: How many emails are marked spams by recipients?
  • Blacklist history: What is the bouncing rate of the emails and whether the IP address is blacklisted in past?
  • Unsubscribed list: How many recipients have unsubscribed from the mailing list of the sender?
  • Spam traps: Here emails are just monitored and not used
  • Email analytics: IP addresses are tracked not only for the number of mails sent but also to check how many of the mails got response like mails are opened and the mails replied etc.
  1. Authentication check/ID proof check

Next check emails have to pass through is authentication of IP addresses. IP addresses of senders are verified to determine whether the senders really want to present their products/services. This check prevents professional hackers from modifying the content before mails are delivered. IP check help determine whether the sender is an Email Villain. A sender is called a villain, if he tries to get personal details of the recipient by phishing or spoofing with a forged address. ISPs are continuously working towards creating more checks to establish reliability of senders and authenticity of emails.

  1. Is the message safe to be delivered – checking the content?

Authenticity of emails is established from their content. ISPs allow mail delivery only after checking its content

  • Malicious embeds: Legitimate looking mails could carry viruses implanted by hackers. These mails, if allowed to get delivered, could take control of the computers and draw sensitive data including passwords. Hackers use this technique by modifying email content.

  • Check spam words and phrases: ISPs read all the content to check spam words and phrases.
  • Link to word ratio: Email content could carry links considered spam by ISPs. There has to be a right mix of content and words in the email content.
  • Text to image ratio: The content shouldn’t be all images. The acceptable ration of text to image is 70:30.

Value of deliverability in email marketing has been discussed in detail in the article and now it is for marketers to make sure that they don’t jeopardize the success of their campaigns by taking the discussed points lightly. These are technical points that guarantee successful delivery but the recipient reserves the right to simply delete a mail or mark it spam. But these factors can also be taken care of with the help of writing and designing.


To make an email marketing campaign a success, the marketers should keep all the technical and non-technical factors in mind. First step is successful delivery that is purely technical and the second step is convincing that is purely human.


Udit Khanna is a Digital Marketing Course professional at Expert Training Institute, an expert in Digital Marketing, Search Engine Optimization, Pay Per Click, Social Media, etc. who helps companies attract visitors, convert leads, and close customers. Previously, Udit worked as a marketing professional for various startups and tech companies. He graduated with B.Sc from IGNOU with a dual degree in Business Administration (Marketing & Finance).

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