The name itself suggests, mailq i.e. “mail-queue”, this command in Linux prints the mail queue i.e the list of messages that are there in the mail queue. You should have a mail-server setup on your Linux machine, in order to use this command, there are ways i.e MTA’s(Mail Transfer agent) you can use like sendmail that uses the service smtp.
The output of mailq command is similar to the sendmail -bp command that also prints the mail queue.
1. maliq without any option: Simply prints the messages in the mail queue.
Mail Queue (1 request) ---QID---- --Size-- -----Q-Time----- ------Sender/Recipient----- SS04506 5 Tue Nov 12 09:01 root (User unknown)
2. Prints along with priority specified: Simply prints the messages in the mail queue.
$ mailq -v
Mail Queue (1 request) ---QID---- --Size-- -Priority- -----Q-Time----- ------Sender/Recipient----- SS04506 5 2005 Tue Nov 12 09:01 root (User unknown)
- QID: Specific ID alloted to message.
- Size: Number of bytes contained in body of message.
- Q-Time Time at which message entered the queue.
Applications: In large applications at production env, email queuing is necessary as recipients are quite good in number, so sending the email to all at the same time becomes a risky thing, so mailq helps in looking out the sequence as per the priority.