[geeks] ADMINISTRIVIA: Changes to mail delivery policies

[Scott Howard]

On Wed, Mar 13, 2002 at 02:12:39AM -0500, Greg A. Woods wrote:
> I just want to point out that your choice of 24 hours is very bogus on
> at least two fronts, and also tell you I'm not the only one saying so.

It's a mailing list. Get over it.

> Secondary MX hosts are very rare and increasingly so.  It is impossible
> to run a secure MTA with a secondary MX that you do not control, so even
> if people do have secondary MXers then they will likely both become
> unreachable when connectivity fails since they'll both be sitting
> topologically side by side on the very same logical IP network.

Poor network design and/or configuration is your problem, not Bill's.

> Personally I find 5 days to be an absolute minimum, and seven days is
> far more sane, even and especially in today's very diverse Internet.

It's a mailing list. Get over it.

> > Yes, I'm turning into a mail BOFH.  If you dont like it, you can unsubscribe
> > or start paying for my bandwidth.  8-)
> 
> The retries (normally just three tiny SYN packets each) for 5 days
> backlog for a few unreachable sites are not going to even be a tiny
> pixel on your bandwidth graph, and I'm sure you won't even notice the
> disk space and other sundry resources they may take up either.

Lets do the sums.  The actual number of SYN packets is going to be closer to
6-8 (remember TCP uses an exponential backoff, so the first retry is sent
fairly quickly, and then more slowly for each one after that).
Each SYN packet is going to be around 48 bytes.
So each failed connection is 6x48 bytes = 288 bytes.
Lets say there's two MX records, and we try both.  288*2 = 576 bytes/try
Sendmail by default retries sending messages every 15 minutes, or 4 times an
hour, giving us 576*4/1024 = 2.25Kbytes/hour
(Yes, I know Bill doesn't run sendmail, but thats what I know)
Do that every hour for 5 days and you get 2.25*24*5 = 270Kbytes per message
So far this month the "Geeks" like has generated about 80 emails per
day (940 messages in just over 12 days), so thats  270Kbytes * 80, or
about 21 MBytes per day!!
If 5 days worth of messages go through before the user is removed from the
list, thats over 100 Mbytes of outgoing traffic _for a single broken acct_

  Scott.