SMTP Server Email Delivery Performance Comparison

Email Marketing is about 2 things – Email Data and Email Delivery.

Without good data and a high email delivery rate the Email Marketer is out of the game.

In this case study we examined the Performance of two SMTP Server Configurations over a 5 week sending period.

Set Up 1 consisted of 1 SMTP Server, Set Up 2 Involved a weekly SMTP Server Replacement.

A total of 1 Million Emails of raw data was sent to identify the best practices for email delivery over the longer period of sending to one server compared to the weekly server replacement setup.

Along with the email delivery variable, we compared the costs per IP and the overall cost per 1Million Email Sent.

Email Delivery Performance in SMTP Replacement Case

In the graphic below it is possible to see the email delivery performance over the two SMTP setups.

Set Up #1 – 1 SMTP Server

  1. SMTP Server x 1
  2. Set of 5 IPs x 1
  3. Sending Domain x 1

Set Up #1 – 5 VPS Configured as SMTP Replaced Weekly

  1. VPS Configured as SMTP Server x 5
  2. Set of 5 IPs x 5
  3. Sending Domains x 5

The left side features the 1 SMTP Server, the weekly replacement for SMTP Server is on the right.


best practices for email delivery


Notice how the email delivery decreases over time when sending the raw data via the same SMTP Server.

The Average Opens Rates over the 5 weeks come in at 2.1%. While the reputation of the SMTP Server declines to an average of 5.2% (according to

In comparison, the weekly replacement SMTP server set up shows that email delivery can be sustained from one week to the next.

Average Open Rates were more than doubled to 5%. Plus the reputation of the SMTP Server fell only slightly from a beginning score of 10%, to 9.5%.



Economic Comparison

Now we compare the prices between the two SMTP Server setups.


best email delivery systems


The average price of 1 SMTP Server with 6IPs is $295 (as you will see on the left).

Whereas the average price for 5 VPS each with 5IPs is $250, a noticeable difference for total unit cost.

However, the most significant difference is in the price comparison per IP. For the single SMTP unit the price per IP including configuration is $49.16. Yet with the multi VPS set up price per IP falls down to only $8.33.


Price Comparison Per 1 Million Emails Sent

The final graphic shows the overall cost for each set up per 1 Million Emails sent.


best email delivery


The numbers here are based on the fact that a dedicated IP can safely send 500 emails per hour. That’s a daily total of 12,000 emails and 360,000 emails per month for each IP.

With the 5 VPS set up the greater number of IPs (30 as compared to 6) offers the user a much greater sending capacity – 12.6 Million as opposed to 2.1 Million. A further big difference is in the Cost per 1 Million Emails Sent. In the 5 VPS setup each 1 Million Emails sent comes down to only $19.



The results of the case study show that the 5 VPS setup, with weekly SMTP replacement,  yields better results for sending reputation, email delivery and cost effectiveness.


Listed below are the Top 5 Benefits:

  1. Increased Open Rates based on Monthly Average
  2. Good Reputation maintained on Email Sending Server
  3. Around 6x to 10x IPs more dedicated IPs for the same price
  4. 10x Less cost per 1 Million Emails sent
  5. Increased Performance and Cost Effectiveness.

Find out more about SMTP Email Delivery


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