On 03.12.18 00:47, Adam Borowski wrote:
> On Sun, Dec 02, 2018 at 11:53:39PM +0100, Alessandro Selli wrote:
> > On 02/12/18 at 17:23, Adam Borowski wrote:
> > > You'd want to set noatime on every machine
> > > you control.
> >
> >
> >   Some mail servers and clients do use it to determine if a mail was
> > read after it arrived.  In this case, it'd be better to have it set on /var.

TL;DR: Use relatime there, as noatime will break mutt.

> That's no more. And, let me clarify: atime was used for mail:
> * only with mbox (Maildir never suffered from this issue)
> * only on the local machine
> * only by the shell to say "You have new mail." vs "You have mail."
> -- not even by the mail client

Not true, according to the on-line manual for my current mutt
installation:

» Other possible causes of Mutt not detecting new mail in these folders
are backup tools (updating access times) or filesystems mounted without
access time update support (for Linux systems, see the relatime
option).«

> So the whole effort gave you just a single word in a message, that many
> people even didn't notice.
>
> And, popular local mail clients are already patched to update atime
> explicitly.
>
> Ie, atime for mail is an ex-reason.

A fine assertion, but wiser is to check the facts. A quick glance in "man
mount" shows:

»relatime
Update inode access times relative to modify or change time. Access
time is only updated if the previous access time was earlier than
the current modify or change time. (Similar to noatime, but doesn't
break mutt or other applications that need to know if a file has
been read since the last time it was modified.)

Since Linux 2.6.30, the kernel defaults to the behavior provided
by this option (unless noatime was specified), and the strictatime
option is required to obtain traditional semantics. In addition,
since Linux 2.6.30, the file's last access time is always updated if
it is more than 1 day old.
«

It would seem then, that noatime will break mutt, but relatime is OK,
and is now the default. IIUC.

Erik