Use the "mailq" Linux Command to Check Pending Outbound Messages

Find Out What's Still Queued for Delivery

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Mailq prints a summary of the mail messages queued for future delivery.

The first line printed for each message shows the internal identifier used on your specific host for the message, with a possible status character, the size of the message in bytes, the date and time the message was accepted into the queue, and the envelope sender of the message. The second line shows the error message that caused this message to be retained in the queue; it will not be present if the message is being processed for the first time.

The status characters are either an asterisk to indicate the job is being processed, an X to indicate that the load is too high to process the job or a hyphen to indicate that the job is too young to process. The following lines of output show the message recipients, one per line.

Mailq is identical to sendmail -bp.

Synopsis

mailq [-Ac] [-q...] [-v]  

Switches

This command's relevant options include:

-Ac

Show the mail submission queue specified in /etc/mail/submit.cf instead of the MTA queue specified in /etc/mail/sendmail.cf.

-q[!]I substr

Limit processed jobs to those containing substr as a substring of the queue id or not when !is specified.

-q[!]R substr

Limit processed jobs to those containing substr as a substring of one of the recipients or not when ! is specified.

-q[!]S substr

Limit processed jobs to those containing substr as a substring of the sender or not when ! is specified.

-v

Print verbose information.

This switch adds the priority of the message and a single character indicator (a plus sign or a blank space) indicating whether a warning message has been sent on the first line of the message. Additionally, extra lines may be intermixed with the recipients indicating the "controlling user" information; this data shows who will own any programs that are executed on behalf of this message and the name of the alias this command expanded from.

Moreover, status messages for each recipient are printed if they're available.

The mailq utility exits 0 on success, and >0 if an error occurs.