Email deliverability basics in Digital Marketing - Time & Space Complexity

Time Complexity: Email deliverability basics

O(n)

Understanding Time Complexity

When sending emails to many people, it is important to understand how the process scales as the list grows.

We want to know how the time to deliver emails changes when the number of recipients increases.

Scenario Under Consideration

Analyze the time complexity of the following email sending process.

for each email_address in email_list:
    check if email_address is valid
    send email to email_address
    log delivery status
    wait for server response

This code sends an email to each address in a list, checking validity and logging the result.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: Looping through each email address to send emails.
• How many times: Once for every email in the list.

How Execution Grows With Input

As the number of emails increases, the total time grows in direct proportion.

Input Size (n)	Approx. Operations
10	About 10 email sends
100	About 100 email sends
1000	About 1000 email sends

Pattern observation: Doubling the list doubles the work needed.

Final Time Complexity

Time Complexity: O(n)

This means the time to send emails grows linearly with the number of recipients.

Common Mistake

[X] Wrong: "Sending emails to more people takes the same time as sending to just a few."

[OK] Correct: Each email requires its own send and response, so more emails mean more total time.

Interview Connect

Understanding how processes scale with input size is a key skill in digital marketing and technical roles alike.

Self-Check

"What if the emails were sent in batches instead of one by one? How would the time complexity change?"