The Courier package contains addcr, authenumerate, cancelmsg, courier, courier-config, courieresmtpd, courierfilter, courierldapaliasd, courierlogger, couriermlm, couriertcpd, couriertls, deliverquota, dotforward, esmtpd, esmtpd-msa, esmtpd-ssl, filterctl, imapd, imapd, imapd-ssl, lockmail, mailbot, maildiracl, maildirkw, maildirmake, maildrop, makeacceptmailfor, makealiases, makedat, makehosteddomains, makemime, makepercentrelay, makesmtpaccess, makesmtpaccess-msa, makeuserdb, makeuucpneighbors, mimegpg, mkesmtpdcert, mkimapdcert, mkpop3dcert, pop3d, pop3d-ssl, preline, pw2userdb, reformail, reformime, rmail, sendmail, sharedindexinstall, sharedindexsplit, showconfig, showmodules, testmxlookup, userdb, userdbpw, vchkpw2userdb and webgpg. cancelmsg removes a message from the mail queue. courier is a modular multi-protocol E-mail transport agent. The courier command is an administrative command, and most of its options are only available to the superuser. courierfilter command installs or uninstalls global mail filters. Global mail filters are used to selectively block unwanted mail. couriermlm is the Courier mailing list manager. filterctl command installs or uninstalls global mail filters. Global mail filters are used to selectively block unwanted mail. lockmail is a helper utility for working with mailbox files.. mailbot reads an E-mail message on standard input and creates an E-mail message replying to the original message's sender.. maildirkw modifies Courier-IMAP compatible maildir message keywords. maildrop is a replacement local mail delivery agent that includes a mail filtering language. makeacceptmailfor Build a list of domains to accept mail for from the /etc/courier/esmtpacceptmailfor.dir directory. makealiases Build a list of aliases from /etc/courier/aliases or /etc/courier/aliasdir directories. makehostedomains Build a database of hosted domains from hosteddomains . makepercentrelay Build a list of %-relayed domains from percentrelay.dir directory. makesmtpacces Build ESMTP server access file from /etc/courier/smtpaccess directory. makesmtpaccess-msa Build ESMTP server access file from /etc/courier/smtpaccess directory. This esmtp list is for the MSA protocol. makeuucpneighbors Builds a list of UUCP recipient's using /etc/courier/uucpneighbors . reformail program reads a message on standard input, reformats it in some way, and writes the message to standard output. reformime is a utility for reformatting MIME messages. sendmail command reads an E-mail message and delivers the message to its recipients. This sendmail command is part of the Courier mail server, although it attempts to emulate the behavior of the original sendmail MTA. showconfig Shows the current Courier configuration. showmodules Shows the current Courier modules. testmxlookup lists the names and IP addresses of mail relays that receive mail for the domain. This is useful in diagnosing mail delivery problems.