[unisog] Size Limit on E-Mail Attachments

Martin Radford Martin.Radford at bristol.ac.uk
Sun Nov 4 00:05:54 GMT 2001

On Fri, 2 Nov 2001, Jim Dillon wrote:

> I have to echo Professor Miller's observation, it does not seem appropriate 
> to arbitrarily limit   the size of email attachments.  If you do not have 
> an architectural limit that causes a system failure or significant 
> degradation of performance, then I'd suggest you avoid strict 
> limits.  

There are essentially two different issues with mailing large files. 
One is whether the *sender's* infrastructure has the capacity to deal
with them;  the other is whether the *recipient's* infrastructure has
the capacity to deal with them. 

Most organisations are likely to impose quotas on their users' 
mailboxes, and it's quite possible that a sufficiently large email will
cause a mailbox to exceed its quota and thus prevent the delivery of
further mail.  If the recipient is on leave, or for some other reason
cannot deal with the problem in a timely fashion, it's likely that new
mail will run the risk of being returned to its sender.

We're currently planning to implement a system for our users which will
allow them to upload large files to a server which will make them
available on the web.  Users will authenticate themselves when they
upload files to the server (so we can identify misuse), and they will be
told the URL for the downloader(s) to use.  Users can then mail the URL
to the files' intended recipient(s).  The files will "expire" after a
fixed period and be deleted from the server.  The URLs will be randomly
generated to prevent them being guessed.

Martin Radford  (Martin.Radford at bristol.ac.uk)
Personal Computer Systems Team
Information Systems & Computing
University of Bristol Information Services

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