The Micro-Deliverability Concept in Email Marketing

The Micro-Deliverability Concept in Email Marketing

Micro-deliverability is a novel notion in the world of email marketing. It entails analyzing deliverability by domains, ISPs, or SMTP Relay servers, and then segmenting the email list or campaigns depending on the findings to get the optimum deliverability and performance for marketing campaigns.

The finest SMTP relay service providers offer overall deliverability rates of more above 96%, however these rates vary depending on ISPs and time.

By carefully monitoring these swings in deliverability trends depending on ISPs and time, one may route emails to various segments utilizing SMTP delivery servers that provide the optimum performance for that specific segment. Using several email distribution systems (Hybrid System) may therefore considerably improve your email marketing performance.

Redundancy (keep your backup plan ready)

We imply having more SMTP relay servers available for usage than you actually need. This redundancy may be a valuable advantage in the worst-case scenario.

When there is a momentary outage or severe decline in deliverability for a certain SMTP relay server (for a specific segment), redundancy allows you to swap the relay server for that segment quickly without affecting performance or deliverability.

ISP Email Filtering and Deliverability Issues

Email filters are a necessary evil, particularly for email marketers. They are a necessary evil for spam filtering. However, valid email messages are occasionally inadvertently classified as spam or sent to the garbage folder.

This is the unintended consequence of email filtering. Many deliverability difficulties are caused by the sender’s reputation, but others are also caused by SMTP relay service providers.

Why are Email Filters Necessary in the First Place?

Spam accounts for approximately 70% of all email sent, according to Symantec. These include phishing communications, viruses, and emails sent by spammers that use this medium for malicious objectives. Inbox delivery would rise if no filter exists.

There will be two spam emails for every good email. This would render the whole email channel ineffective. ISPs censor emails because of email spam.

Causes of Email Delivery Problems

A legal email might wind up in the spam bin rather than the inbox for a variety of reasons. Some of them are tied to the sender’s reputation, while others are related to the sender’s email service provider.

Problems with the Sender

The reputation of the sender is taken into account when determining whether an email will be sent to the inbox or the spam bin. The sender’s reputation is determined by a number of criteria. These elements are as follows:


ISPs depend significantly on authentication to ensure that the email was sent by the claimed sender. ISPs do authentication using one of three main methods:

  • Framework for Sender Policy (SPF)
  • Sender Identification
  • Mail Identified by Domain Keys (DKIM)
  • Reporting and Conformance for Domain Message Authentication (DMARC)

These authentication techniques enable ISPs to compare email information with the email sender’s DNS data.

If the email address does not match the DNS address, the email is more likely to end up in the recipient’s spam folder than than the inbox. The sender’s reputation will suffer if authentication is not implemented.

2. Complaints about spam

If receivers report the sender’s emails as spam, the sender’s reputation will suffer. Spam complaints should account for less than 0.1% of overall email volume. In the event of 0.1%, the sender’s reputation suffers on a continuous basis.

3. Bounce Control

When emails bounce, the sender’s reputation suffers. It indicates to ISPs that the sender’s email list is dirty. Hard bounces are removed after one occurrence and soft bounces after three successive deliveries, according to industry standards.

4. Participation of Recipients

When the people to whom the sender is sending emails do not open such emails, the sender’s reputation suffers. In other words, the rates of clicking/opening are low. This information indicates that the receivers to whom the sender is sending emails are not sufficiently engaged in those communications.

SMTP Relay Problems

Email deliverability is hampered by SMTP relay difficulties. The most prevalent issue is with shared IP addresses. Despite the fact that ISPs are moving toward domain-specific filtering, the majority of ISPs still filter at the IP address level.

This implies that if an IP address sends emails that are considered as spam, all emails from that IP address will be prohibited, regardless of the site from which they are sent. Even with a dedicated IP address utilized by a single company, SMTP relay side deliverability difficulties might occur.

Challenges in Optimizing Micro-Deliverability

1. There is a lack of data on micro-delivery

Monthly or quarterly, SMTP relays report their total deliverability rates. They just lack the means to update more regularly.

Yet even in these sources, the reported deliverability percentages are aggregate figures, not breakdowns by Domains/ISPs. Micro-Deliverability optimization is not possible with these global rates.

2. Time Constraints

The time required to organize the data for Micro-Deliverability Optimization and then utilize it for email segmentation makes it impractical for email marketers to carry out such tasks.

3. One Standard Message Transfer Protocol (SMTP) or One Electronic Mail Service Provider (ESP) Infrastructure

Most businesses only use one SMTP or ESP configuration. This is due to the fact that it is impractical and time-consuming to learn and utilize several ESP or SMTP relay interfaces, send emails from various SMTP interfaces, and aggregate the performance statistics from each.


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