Which of the following is NOT a common troubleshooting action for email issues?

Changing the subject line is not typically considered a common troubleshooting action for email issues. When addressing email problems, actions usually focus on identifying and resolving issues related to delivery, reception, or filtering of messages.

Checking spam folders helps ensure that emails aren’t being incorrectly marked as spam, which can prevent important messages from being seen. Updating the recipient list can resolve issues related to sending emails to incorrect or outdated addresses, which is crucial for successful communication. Reviewing bounce-back messages aids in diagnosing why emails failed to deliver, providing insights into possible issues like invalid addresses or server problems.

In contrast, modifying the subject line does not directly address the underlying problems that may cause emails to fail to send or be received correctly, making it less relevant in the context of troubleshooting email issues.