Email Deliverability And Factors Affecting It

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At our goal is help our users find best jobs any time any where. Users can search jobs on our website as well as they receive job alerts as per their requirements.

We send close to 25 crore emails on a monthly basis to our users. As a result, email deliverability is very important for the success of our business.

Keeping that in mind let us see what email deliverability is and what are the factors that may affect the delivery of an email.

Email Deliverability is a way to measure the success at which an email marketer gets a campaign into subscribers’ inboxes. It involves anything that touches email delivery, like ISPs, MTAs, throttling, bounces, bulking, and spam issues.

We, at naukri, do take into account the factors that may affect the delivery(inbox) of our mails. Few factors that play an important role in the email delivery are :

1) Message Infrastructure Health

Network and Infrastructure used have a huge impact on message delivery. It is important to rely on a secure infrastructure by following the best practices of network and physical security to avoid access by unexpected users.

SMTP assumes the presence of reliable network connectivity and name resolution through the Domain Name Service (DNS). Anything that interferes with these functions can prevent messages from being delivered. We have a state of art infrastructure to send and monitor the email traffic.

2) Message Content(Data)

Mail message content is very important. Recognizing a message as spam or malware by examining its content (including attachments, URLs, message text, and headers) has proven to be a pretty good way to identify and block unwanted content.

Headers specially play a crucial role in recognizing a message as it acts like a business card. Whenever an email is send,the email servers provider communicated with the recipient’s email server.

Sender server sends the header message to the server of recipient.Thus if the receiver’s server will not like header of the mail, probably it will not accept the email.All our mails are passed through spam check algorithm to remove any unwanted emails.

Also, one should take care of the sender’s correct identity i.e. sender’s email. If the from email address is different from the actual sending server’s address, then the recipient server considers the email header as fake.

3) Sender’s Reputation

Next big thing is the reputation that you own. If the reputation of a sender is bad, even if your infrastructure is in place and even the content is the best one can provide, the mail can be rejected.

If recipients are opening and interacting with the emails, this will positively add to the reputation with ESPs. If however the content is not engaging, nobody interacts with the emails than the reputation can start declining.

Sender reputation is based on its history of activities(mails send in the past were good or were marked as spam). A sender’s reputation depends on various things :

  • IP reputation : If an IP address consistently delivers good email, then it is very likely this new email is good, too.Conversely, if an IP address consistently sends bad email, then it is very likely any new email it sends is bad, too.IP reputation can also turn bad if a cold IP address is used. Cold Ip address is a new IP through which you start sending big volumes of data. Before using an IP for regular use, one must warm it by increasing the volume slowly and consistently starting from a small volume. And so, before using any new IP for regular use, we insist to warm up the IP by sending low and consistent data and raising it slowly and steadily until it is ready to use on regular basis.
  • Domain Reputation : As soon as a domain is created, that domain starts to build a reputation. This can go up and down depending on a number of factors including design, content and engagement.One of the most important ways of building reputation is to send engaging content. Building a negative reputation can lead to blacklisting. As the IPs and content of our mails are in place, our domains hold a good reputation and hence helps us in avoiding the blacklisting.
  • Spam Complaints : Sending unsolicited mail, results into SPAM complaints. We ensure that users have opted in to receive the mails. We also enable our users to unsubscribe easily from the mail itself by providing an unsubscribe link. This helps reduce spam complaints.
  • Spam trap email addresses : The email ids must be verified. There are such email Id that are never published or shared anywhere. these IDs are used to trap Spammers. Hence the emails must be verified before sending mails to keep the sender’s reputation intact. Same is the case with bounces. the bounce rate must be low for the maintenance of a good reputation.The receivers of our mails here at naukri, are the people who register themselves at and provide their email Ids which in turn strikes out the possibility of us being trapped in Spam trap email addresses.
  • Inconsistent Volume and Frequency of Emails : Emails must be triggered at a consistent rate and consistent volume. i.e. if the emails are send randomly at any interval ranging from a day to a week and a month and if the volume varies like 5000 then 20000 then 20 and then 50000, it is most likely that the sender would be flagged for inconsistent frequency and volume. the mails count at our end may vary from 70 lakhs to 1 crore on the daily basis(weekdays) for naukri mails keeping in mind the frequency and volume both to be consistent.

4) Email Authentication : This acts as a signature i.e. it verifies the identity and allows to claim responsibility for the mailing servers. It plays a vital role in detection of Spam mails as spammers generally try and forge someone else’s identity. Authentication is essential for securing your brand and preventing spoofed messages from damaging your online reputation.there are various ways to authenticate emails. Some protocols does the sender authentication whereas some do content authentication.

Sender Authentication Protocols

a) SPF(Sender Policy Framework):

SPF protects the envelope sender address, which is used for the delivery of messages. The envelope sender address (sometimes also called the return-path) is used during the transport of the message from mail server to mail server, e.g. to return the message to the sender in the case of a delivery failure. It is usually not displayed to the user by mail programs.

So precisely, SPF allows the owner of a domain to specify their mail sending policy, e.g. which mail servers they use to send mail from their domain. The technology requires two sides to play together:

(1) the domain owner publishes this information in an SPF record in the domain’s DNS zone and when someone else’s mail server receives a message claiming to come from that domain, then

(2) the receiving server can check whether the message complies with the domain’s stated policy. If, e.g., the message comes from an unknown server, it can be considered a fake. We get the SPFs assigned for the IPs that are designated to different domains. for instance, all the IPs assigned to naukri have their SPFs binded to domain.

b) Sender ID : Sender ID is a Microsoft protocol derived from SPF that authenticates one of the header addresses. Which one it authenticates is selected according to an algorithm called PRA (Purported Responsible Address). The algorithm aims to select the header field with the e-mail address “responsible” for the message.

Although Sender ID uses DNS records with a nearly identical syntax to SPF, and even uses the letters “SPF” in its version string (“spf2.0/pra”), it is not the same protocol because it authenticates the PRA header identity, whereas SPF authenticates the envelope MAIL FROM identity. Today it is used very less. Even Microsoft has migrated away from using Sender ID.

Content Authentication Protocol

a) DomainKeys Identified Mail : DKIM provides a cryptographic signature of multiple header fields and the body of a message. A domain protected by DKIM publishes in a DNS record the public key (“domain key”) corresponding to its self-generated private signing key. Receivers can then use that key to verify the authenticity of the message header and body with regard to the header sender identity.

The concept of DKIM is a hybrid of sender authentication and content authentication as it strictly ties the authenticity of the message content to the message’s alleged sender identity. I.e. in order for a message to be regarded as valid, it is not enough that its signature can be successfully verified but the sender domain in the message header must also match that of the signing key. We also use DKIM in our authentication process to be completely secure.

As discussed so far, we take care of our email infrastructure very seriously and keep on improving our content and process to keep email deliverability high. To know more about how we manage high email volume, drop your comments below.