remove from list

five methods:
1. you can create their accounts in your POP3/SMTP mail-client and write from their name. you have to enable relay for those accoutns on your SMTP server.
2. if those people had e-mail inside your company you can create their accounts on your server like Exchange and do same as above with Outlook etc.
3. you can read RFC for SMTP protocol and emulate mail session via telnet. but you have to get MX host for mail-list first via nslookup, for example. then you connect to desired host port 25 and type seven lines of text:
---
helo test
mail from: your_people@domain.com
rcpt to: maillist@destination.com
data
subject: remove

remove
.
---
problem is that you don't know format of remove message.
4. you can write to according postmaster@mail-list-host.server - he should help you :)
5. don't do anything if your server sends reply with message like "this user isn't exists" or if your server answers in SMTP session with corresponding error code, so you even will notreceive those messages from maillists. but you need to check documentation for your mail server, how to bar those addresses. sometimes there is multiply choises like reject mail, forward to postmaster, forward to other box etc. you can choose best strategy.