I've found both the problem and the communication issue that's not letting us get to the heart of the matter.
Note that I'm using the most recent version of DirectAdmin; earlier versions didn't allow this setting.
When visiting CMD_SHOW_USER?user=bob (replace bob with a valid username on your system) when logged in as a reseller, you can see the email limit for the user, and the current emails for today, but you can't change them.
Using the same CMD call (in your browser) logged in as admin, you can change the limit and reset the daily limit.
But you can't set the daily limit to higher than the max_per_email_send_limit John refers to in his post above. To do that, you need to set it manually.
My usage is the same as user Arieh, and I agree with him it would be nice to be able to do it from the Control Panel rather than by logging in through the shell.
I humbly suggest to John that Arieh and I, and probably others, use a relatively low default server limit (250 or 500) and then set higher limits for clients who demonstrate to us that they need them, and that they keep their software up-to-date so it's less likely to be hacked.
For example, on a shared server, I have two hundred clients and I limit each one to 250 daily emails. This has the effect of making it unlikely that even if a user gets hacked, I'm likely not going to have my server on a blocklist. But one of those users runs a carefully managed website and a carefully managed double-opt-in list he wants to run on our server. I'll let him, by setting a limit of 1000 daily emails for his account. Currently I must do that through the root shell; I'd rather be able to do it through DirectAdmin.
Please, John, would you consider removing the limit? Since it's over-ridable at the root level is there a reason to have it at the DirectAdmin level?
Thanks.
Jeff