With all of what? All email programs?
It looks to me like “blocking” someone in gmail just causes their mail to you to be automatically placed in your Spam folder. It doesn’t let the sender know you’ve done that. I confirmed this by testing blocking another email of mine from gmail and then emailing myself at gmail. I didn’t get any kind of notice that the email had been filtered to Spam.
Other webmail systems and actual email programs I’ve used (e.g. Eudora, Thunderbird) do the same thing, as usually they assume you wouldn’t want someone to know you’re ignoring their email (because they’re spammers just trying to find out if there is a valid email address, and/or they will them know to try sending from a different non-blocked email address).
If you do want someone to know, then you can set an auto-reply, at least on some systems.
The gmail help confirms this is what it does .
And the steps for configuring gmail with an auto-reply to certain users are apparently:
1. Enable Settings->Labs->Canned Response
2. Create and save a Canned Response
3. Edit the filter and on the second page check the box to have it send a Canned Response back to the sender.