.forward files 

Files that can be set up in a user's home directory to redirect mail or send mail to a program automatically 

mailbox 

A file on a mail server that is the final destination for email messages 

mail addresses 

Contains the name of the recipient and the system to which a mail message is delivered 

mail aliases 

An alternate name used in a mail address 

mail queue 

A collection of mail messages that needs to be processed by the mail server 

postmaster 

A special mail alias used to report problems and ask questions about the mail service 

sendmail configuration file 

A file that contains all the information necessary for mail routing