What is the purpose of the postmaster, webmaster, etc. email addresses?

I guess the following email address are frequently (if not always) used : postmaster@domain, webmaster, abuse, services...

But what are their purposes ? Why create them ?

Thanks :)

It's so there are well-known contact addresses.

• postmaster is whoever operates the mail server.
• webmaster is whoever operates the web server.
• abuse is whoever handles what are likely violations of the Terms of Service (so these commonly exist on providers).

Generally, if I find some other mail server misbehaving (e.g. not accepting mail when it should), I contact the postmaster, and when I find a problem on a webserver (e.g. someone hosting a virus on a hacked machine) I contact the webmaster.

In general there is an expectation that if you find a problem, you notify people before it grows, and if you provide a service, you should be easy to contact.

We get very little spam on these well-known addresses, probably because spammers have learned that they generally connect to people who are able to track down spam to its source and forward it to the appropriate abuse address with a request to look into the matter, so that is an excellent way to get your operation shut down.