Analyzing POP, IMAP, and SMTP problems
In this recipe, we will discuss the use of Wireshark to analyze failures in email protocols.
Getting ready
When the failure is reported by a specific user while all other users are working fine, capture the packet as close as possible to the affected user. If the failure is reported for multiple users, capture the packet as close as possible to the server.
How to do it...
Depending on the direction of the failure, we may need to identify what email protocol we should be troubleshooting.
For example, if the user complains about a failure when sending email, we need to focus on SMTP, and if the failure is with receiving emails, we need to focus on IMAP or POP3 (depending on the protocol used by the client).
- Once the direction of failure is identified, check that the TCP session for the relevant port is established:
- The preceding screenshot capture shows that the client is not able to establish the TCP session to the server on port
143. In this case, we should...
