You can create additional mail files by using the copy or move commands to copy mail you have received, or by using the fcc command or saved-messages-file variable to keep messages you send.
One mail file, usually named mbox, is the main mail file, where all incoming mail is received. Use additional mail files to organize your mail in any way that is logical to you. You can move around easily from one mail file to another with the get or examine commands.
Use the command get with the name of any mail file to visit that file. All MM commands will then apply to that mail file. The mail file you are visiting is known as the current mail file.
MM>get oldmail MM>
In the above example, oldmail is a mail file, that is, a file of mail messages.
If you use the question mark after the command get, you will see listed all the files in your mail-directory. Some may not be mail files. If you try to get a non-mail file, you will see an error message:
MM>get ? mail file . .. .mmfast .mminit .noteseq .notesrc .plan .plan~ .profile .project .project~ .sh_history .signature mbox mbox~ oldmail subways MM>get subways File is damaged or in unknown format: /f/u1/d00000/yourid/subways MM>
The error message is not a problem unless subways is supposed to be a mail file. If it is actually a file of text you were writing, or a program, or anything else, then the error message is just stating that the file can't be read as a mail file, which makes sense. If it is a mail file, contact your systems staff for help; the damage could be very minor, even one character added or missing at certain locations.
To return to your main mail file, mbox, you can specify it by typing get mbox, or just type get.
The examine command is the same as get, except that examine allows only what is called read-only access. If you visit a mail file with examine, the mail file on your disk will not be changed, no matter what commands you give.
MM>examine oldmail MM>
One reason to use examine is to protect a file from accidental changes. For example, you might keep some very important messages in a separate mail file, and only examine that file to avoid any chance of deleting them.
Another use of examine is to look at someone else's file, if they have changed the file permissions to allow you to do so. Only one MM process (session) at a time can get a file, but multiple processes may examine it. The reason for the rule is that get access allows changing the file, and strange things could result if two or more processes were trying to make different changes to one file. Read-only access with examine presents no such problems.
If you examine your main mail file, mbox, you cannot receive new mail or mark messages as read, since both would require writing to the file, which you cannot do with read-only access. Normally, use get to return to your main mail file.
The aspect of examine that can cause misunderstanding is that you can change the temporary copy of the file that you are looking at. You can for example delete and flag messages, edit messages, and so on. The important thing is that none of the changes will be saved. When you are through, the mail file on disk will be exactly the same as it was when you started.
The behavior of examine can be be modified by changing the variable modify-read-only, which is normally set to yes, permitting you to change the temporary copy of the mail file that you are looking at, as just described. If you reset it by typing set modify-read-only no, then you will not be allowed to change even the temporary copy: if you use a command like delete, an error message will appear.
The command expunge applies only to the current mail file, and only when you have write access to it with get. Likewise, leaving MM with the exit command expunges only the current mail file you were in when you used the exit command.
Whenever you have deleted messages in a mail file, you may want to use the expunge command on that mail file before you change to another.