RMS posted:

After your message arrives at gnu.org, I will collect it in my next batch of
incoming mail, some time within the following 24 hours. I will spend much of
the following day reading that batch of mail and will come across your
message at some point. If I write a response immediately, it will go out in
the next outgoing batch--typically around 24 hours after I collected your
message, but occasionally sooner or later than that. Please expect a minimum
delay of between 24 and 48 hours in receiving a response to your mail to me.

If your message is hard to understand or responding takes real work,
the response could take longer.