How can I send e-mail (e-mails about same content) to different
internet users;in other words I mean sending same e-mail to bunch of
people (not knowing of their e-mail addresses).Is it possible?

Unless I misunderstand your question, the Answer is NO. If you want to
send someone an email, you must know their email address. Think of an
email address as a street address, an 'electronic mail' address. Could
you send your friends a "Christmas Card" through the Post office
without knowing where they live?

John Doe
123 Any Street
Your town, State, 12345

...is the same as:

johndoe@hisemailprovider.com

No address, no delivery.

~~Cynthia

Theoretically, you could do this by setting up a mailing list.  If you
could somehow induce the desired recipients to subscribe to the list,
you could send them mail by sending it to the list address, without
knowing their individual addresses.  If these people are, say,
visiting your web site and want to receive the content, this could
work.

So a relevant question is:  how do you want these people to be
identified or selected?  If they are just people you happen to know in
the real world, see Cynthia's comment.