单选题A user can receive email but cannot send email with the email client software. Which of the following protocols is incorrectly configured?（）A FTPB SMTPC POPD SNMP
题目
单选题
A user can receive email but cannot send email with the email client software. Which of the following protocols is incorrectly configured?（）
A
FTP
B
SMTP
C
POP
D
SNMP