Re: Mail : quota or not quota ? and how to ?
On Thu, 17 Feb 2005, Emmanuel Halbwachs wrote:
1. Quota or not quota ?
To my mind, the pros :
- some indelicate users won't block some delicate ones
If a disk fills mail will tmpfail so a user don't lose mail if another
user fills the disk, as long as it is cleaned in a reasonable amount of
time. OTOH, a full disk will precent the sending of mail. Many MUAs
(mail user agents) only point this out after you've tried to send.
and cons :
- If a user goes on holidays and receive a lot of useless mail (spam,
jokes from friends with giant MS powerpoint attachement) and
Have a reasonable maximum file size for delivery. Email is a terrible way
to send large files anyway thanks to the encoding that is needed for the
attachments. Businesses these days often want 50 or 100MB file limits
5-10MB is better.
reaches his quota, some useful mail will be bounced as the
housework cannot be done by this off-line user
The solution to this may be to allow a smallish soft limit with a large
hard limit and a grace period long enough to surive the holiday break of
most employees. Allowing for a large hard limit and a long grace period
does somewhat mitigate the advantages of quotas in the first place though.
An alternative may be to allow a largish hard limit all the time,
with users on a fairly short grace period (say 7 days) but extend the
grace period when someone is on leave. This would require interfacing
with the HR dept and making sure the procedures were followed. This way
the email is kept while they are on leave but they must cleanup when they
return.
- spending endless time to administer quota and discussing with users
"I am a power user, I need more space than this user", "I am in a
hurry, don't have time to do housework, but I need to receive
urgent mail", etc.
Get the backing of management to make this a solid policy. Eg, the
person's department head must authorize an extension of quota.
2. How to implement quota the best way (and the easy way on Debian) ?
The xfs filesystem is often considered to have a superior quota system to
other filesystems on Linux.
I don't know how mail quota is implemented.
Just quota whichever filesystem the users store their mail files on. They
may have their inbox in /var/mail and their other folders in $HOME, sojust
quota /var & /home.
Ideally, I would like thoses features :
- a soft and hard limits
Absolutely. I'd see this as essential. Have the system notify you and
them when they are over the soft quota. Debian has tools that does this.
- when over the soft limit, user can receive mail but not send
I think this is a bad idea from a business point of view and from the
point of view of being useful.
If you impede their ability to do their work you will get a very bad
reaction from them.
- users are well noticed, whatever the MUA is. A information mail
seems to me the best way. Perhaps one notice each time the user tries
to send mail
I would avoid this. The standard tools send 1 email per day by default
alerting the user to the problem.
- when over the hard limit, user can't receive mail, and is noticed
Be default mail will perm fail when they are over the hard limit (or over
the soft limit once the grace period is over).
Rob
--
Robert Brockway B.Sc.
Senior Technical Consultant, OpenTrend Solutions Ltd.
Phone: 416-669-3073 Email: rbrockway@opentrend.net http://www.opentrend.net
OpenTrend Solutions: Reliable, secure solutions to real world problems.
Contributing Member of Software in the Public Interest (http://www.spi-inc.org)
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