The site I'm developing has various scripts which generate e-mails. For example, there's a registration script which sends a typical confirmation message to a new user's e-mail address; a forgotten password script to send them a temporary-access password; an RSVP script to alert an organizer when someone expresses interest in attending their event; and so on.
Although I do implement CAPTCHAs, I do worry that someone abusing these scripts, or even a short burst of unusually heavy activity, could cause me to exceed the limit of
x number of messages per
y interval of time. That's why I'm writing a function to prevent (and postpone) any further mail from being sent if too many messages have been sent in the past
y interval.
My questions are these: is there such an official limit and, if so, what is it?
In the following three threads...
-
Newsletter script vs. mass mailing?
-
Clean Educational Site Closed for Abuse!!?
-
Phpbb, image hosting, mass mailing
...
people assert the limit is twenty e-mails per minute. Those threads all seem to be from mid-2008.
On the other hand, the thread we're in here and this one are slightly more recent (January and February of this year), and both contain claims that the limit is just ten e-mails per minute... and here that notion is put forth by the same
sizzlefire who said it was twenty in
this thread...

It's a pity, that inconsistency, because as far as I can tell, he/she is the only authoritative person to have cited figures about this. I didn't see any numbers given in the terms of service, as someone else suggested consulting.
So to clear the matter up, was the limit twenty/minute before, and was it later lowered to ten?; or is one of those two figures a mistake, and the other the correct one? Or does an official guideline exist at all?
I'm definitely not trying to create any mass-mail; on the contrary, I'm trying to make dead sure I obey set limits, and that's why I want to be sure of what they are!
Thank-you...