Mail command hangs

If the mail(C) command hangs when a user tries to read mail, check the following:

1. Verify that the user's mailbox exists in the
   /usr/spool/mail directory. Unless your system was configured differently as described in ``Specifying the location of user mailboxes'', the /usr/spool/mail directory should contain a file for each user who receives mail.

2. Make sure that the owner and group ID of the /usr/spool/mail directory is mmdf.
   

3. Make sure that the mailbox is not too large (1000 messages is regarded as too large).

4. Check for these lock files:
   
   /usr/spool/mail/user_name.lock
   /tmp/user_name.mlk

   user_name is the user's account name. If a lock file is found, remove it with this command:
   
   /usr/mmdf/bin/cleanlck