Hy,

im running sendmail and would like to add new addresses to it. One way is to create system accounts and then eventually use aliases file. But i think creating a huge number of system accounts just for these purpose is pretty unsecure. Can i run sendmail, using just one system account and add others just to sendmail? and how can i do this?

Let me illustrate the situation with an example:
i have a system account named info and e-mail address info@zwars.com
now, i'd like to add e.g. 20 e-mail addresses, like: person.one@zwars.com..., but i don't wat to create for each one of them a system account. How can i do it?

It is possible but it really depends on what MTA you are using and how/where you want to store the e-mails.

Without creating system accounts, you must either send all the mail to your one account or forward it to other account on a remote system. All of this is done through the aliases file. If you want each mail address to be delivered for pickup by a separate person, then you must create a system account for each person (you don't need to use the alias file if they have a system account).

Assuming you don't need wildcarding, your sendmail aliases file should do the trick - man aliases(5).