Open rate sampling (ORS) is a process of email deliverability testing in which email providers attempt to send email messages to a selection of email addresses to determine whether the messages will be accepted or rejected. This type of testing is typically performed by email service providers (ESPs) when they are setting up new accounts or making changes to existing ones. ORS can be used to test various aspects of email delivery, including: - The ability of the ESP's servers to connect to the email server(s) of the recipient(s) - The ability of the ESP's servers to authenticate with the email server(s) of the recipient(s) - The ability of the ESP's servers to deliver the message  

Open rate sampling provides a number of benefits, including:

- More accurate measurements of open rates.

- The ability to track changes in open rates over time.

- The ability to compare open rates across different email campaigns.

- The ability to compare open rates across different groups of subscribers.

- The ability to identify trends in open rates.

- The ability to identify potential problems with email deliverability.

- The ability to provide data for A/B testing of email campaigns.

- The ability to segment subscribers based on open rate.

The click-through rate (CTR) is the ratio of the number of users who click on a specific link to the total number of users who see the link. The open rate is the ratio of the number of email recipients who open an email to the total number email recipients.

Open rate is a metric that measures the percentage of email recipients who open an email. A good open rate varies depending on the industry, but generally speaking, a good open rate is above 15%.

According to a report from email marketing firm Litmus, the average open rate for email is 21.33%. However, open rates can vary greatly depending on the industry, type of email, and other factors. For example, welcome emails have an average open rate of 70.19%, while promotional emails have an average open rate of just 18.80%.