With recent Stretch installations the “mail” (or “mailx”) command is satisfied by the s-nail package. As it comes fresh out of the box, s-nail has a problem with dotlock files. For example:
> rbthomas@half:~$ mail > Creating dotlock for "/var/mail/rbthomas" ..... > Unable to (dot) lock mailbox, aborting operation: Permission denied > Creating dotlock for "/var/mail/rbthomas" ..... > Unable to (dot) lock mailbox, aborting operation: Permission denied > rbthomas@half:~$ I don’t know if this is deliberate, or even whether this is the right fix, but the error can be made to go away by doing: > sudo chown root:mail /usr/lib/s-nail/s-nail-privsep > sudo chmod g+s /usr/lib/s-nail/s-nail-privsep If the consensus is that it’s a bug, not a feature, I’ll submit a bug report. I guess s-nail is the appropriate package? Enjoy! Rick
