Re: [Emailcore] Proposed ESMTP keyword RCPTLIMIT
Mike Hillyer <[email protected]>
| Newsgroups | gmane.ietf.smtp |
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| Message-ID | <BN6PR22MB022669CD015B89D47AA063F3DA489@BN6PR22MB0226.namprd22.prod.outlook.com> |
Generally speaking when I advise senders on their rate limits, I have them use the smallest denominator possible, because most commercial MTAs will take a per-hour rate limit and implement it as "send the hour's allotment in a single burst and then wait 59 minutes", which I don't think most receivers want, so I advise setting a per second limit when possible. One message per second is better than 3600 messages per hour if it means a 3600 message burst and then a long wait. Mike -----Original Message----- From: ietf-smtp <[email protected]> On Behalf Of Ned Freed Sent: Monday, April 19, 2021 7:34 PM To: John R Levine <[email protected]> Cc: Ned Freed <[email protected]>; [email protected] Subject: Re: [ietf-smtp] [Emailcore] Proposed ESMTP keyword RCPTLIMIT > On Mon, 19 Apr 2021, Ned Freed wrote: > > I'm especially interested in people's thoughts on rate limits. The > > problem I have with rate limits is, well, how to express them. ... > A little surveying might be in order. > I see that Postfix lets you set both the numerator and denominator of > the rate limit, but the denominator defaults to a minute. It has > separate rate limits for connections and messages. > Exim also lets you set both, the examples use an hour. The > documentation says that if you use a large interval that lets people send bursts. Sounds familiar. Oracle Messaging Server lets you set both; the denominator default is one hour. We store the limits in memcache or Redis so they can apply across mutiple MTAs. The usual limit is per-IP, but we support per-host and per-domain as well. The demoninator in PowerMTA is a string rather than a number, possible values are sec, s, min, m, hr, or h. It supports per-IP and per-host and probably other stuff; my familiarity here is limited. I assume the Exim and Postfix limits are per-host, which in most cases translates to per-IP. I have to say there's more consistency here than I expected. Ned _______________________________________________ ietf-smtp mailing list [email protected] https://www.ietf.org/mailman/listinfo/ietf-smtp