What would a network analysis use Wireshark to analyze SMTP or POP?

Write a 2-3 sentences overview paragraph of what is SMTP and POP3.  Answer the following:  What would a network analysis use Wireshark to analyze SMTP or POP?
Write a 2-3 sentences overview paragraph of what is DCHP.  Answer the following:  What would a network analysis used Wireshark to analyze DHCP?
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