If you enabled autoresponder in your cPanel, then you probably noticed that, by default, the sender gets only one autoreponder message every 8 hours. There is nothing wrong with that. In fact, the purpose of this interval setting is to prevent sending a bunch of emails to the sender who sends more then one email to the user who has enabled autoresponder.
The problem
But what happens if you enable autoresponders for multiple email accounts on the same domain? Well, if the sender sends an email to Bob he’ll get Bob’s autoresponder message. If the same sender decides to send an e-mail to Alice couple of minutes later, he won’t get Alice’s autoresponder message. The culprit? Yeah, that damn interval!
Unfortunately for you (but not server administrators), cPanel doesn’t let you set an interval lower that 1 hour. Moreover, you won’t be able to disable the interval with 0 because this value will simply be disregarded.
The solution
However, there is a solution for this problem. If you peek into /home/username/.autorespond/ directory, you will find a .json file for every email address that has autoresponder enabled. If you open one of those files, you’ll notice something like
{"start":null,"stop":null,"interval":"3600"}
You guessed it - these files contain start and stop dates for autoresponder as well as interval value. So instead of 3600 (or whatever the value in your case is), you can set custom interval value in seconds.
So, 3600 would be 1 hour, 1800 would be 30 minutes, 60 would be 1 minute and so on.
Don’t be stupid
If you receive a lot of emails, don’t set low interval value because the senders will receive the same autoresponder message over and over again, which is very annoying. Also, your mail server may use a lot of system resources in case of high email traffic.