The mailq command lists any outgoing email messages awaiting delivery:
# mailq
Queue ID- --Size-- ----Arrival Time-- -Sender/Recipient--
46AAB43972* 333 Tue Jan 10 21:17:14 smith@example.com
jones@elsewhere.org
Sent mail messages are also recorded in a log file, /var/log/mail.log.
mailq Command Examples
1. To see the mails in queue:
# mailq
2. To show the mail submission queue specified:
# mailq -Ac
3. To show the “lost” items in the mail queue instead of the normal queue items:
# mailq -qL
4. To show the quarantined items in the mail queue instead of the normal queue items:
# mailq -qQ
5. To Limit processed jobs to those containing substr as a substring:
# mailq -q[!]I substr
6. To Limit processed jobs to quarantined jobs containing substr as a substring:
# mailq -q[!]Q substr
7. To Limit processed jobs to those containing substr as a substring of one of the recipients:
# mailq -q[!]R substr
8. To limit processed jobs to those containing substr as a substring:
# mailq -q[!]S substr
9. To Print verbose information:
# mailq -v
Note
Sendmail is an intelligent mail agent, and it tries to deliver mail even when failures occur. For example, if a user attempts to send an email to user@hostname.com, and the mail server for hostname.com is turned off, sendmail will be unable to make a connection to TCP port 25 on the mail server for hostname.com and consequently won’t be able to deliver the mail. Instead of giving up, sendmail will place the email in a queue and attempt redelivery. The default action of sendmail is to attempt redelivery of queued mail every 4 hours for 5 days before giving up and sending a “Delivery Failure” notification to the original sender. Queued mail is stored in the directory /var/spool/mqueue and is managed by the program mailq.