I finally seems to succeed to make it work out...
I use an external DNS server for my mx record..it seems that i have no problem now to accept out of my network mails..but looking to have prolems to accept from my internal network.

it will be surely a setting of my mail.cf

thank you all for your help ..i really appreciate this a lot..

no, it's much more likley to be about routing and general networking. the only difference with internal and external from the mail server would be the source address in mynetworks, which are apparently already correct.

If you are trying to relay from outside (so sending from external sources to anything other than local addresses), you need to be very careful not to set yourself up as an open relay. You should probably look into sasl authentication and TLS to encrypt the sending of authenticating usernames/passwords. Be careful changinf postfix restrictions.

If you internal clients are resolving to the envernal IP, then you'll have issues.

On the client machine, try adding

internal.IP.of.server smtp.netconfig.gr

and then point your client to relay through smtp.netconfig.gr or to otherwise send through than hostname

Really a big thanks to all of you for the time you spent and your support.

I really wouldn't have succeeded without you.

I finally did make to setup this.

I currently have a Win server that i use for mail server and i want to change to centOS, so that i do all these.
At Win server i use for mail server i have several mail accounts for ex. :
test1@example.com
test2@example.com
test3@exmaple.com
test4@exmample.com

and groups:
group1@example.com
group2@example.com

abnd i assign each user to respective group that will receive mail from
for ex.

test1@example.com and test2@example.com receive mails from group1 mail account
and
test3@example.com and test4@example.com receive mail from group2 mail account

Outside network they sent mail to group mail addresses,, and then i assign these mails per user.

How this can be done to Linux?
I hope that i let you understand

Thank you very very much

For the groups, you can just use alias entries. I don't know an automatic method for this

Any guide on how we can create alias pls?

Thank you

just read the aliases manpage.

thank you very much for your reply..

i will give a try

You can use the aliases file in /etc

Add entries like

group1: user1, user2

then run newaliases

Alternatively you can set up aliases in ldap or one of the sql databases

Edit - sorry sat on this post for a bit

You may also find www.postfix.org/DATABASE_README.html useful

which one you think with your experience that is the better for implement what i want ?

Thank you

How many groups/users are you talking about

I currently have 15users as : user1@example.com ... user15@example.com to whom i distribute mails from groups they are assign to.

i currently have 10groups as: group1@example.com...group10@example.com which are mail addresses that outside sent to me.

Each user can receive mail from more than 1 group.

For example i have user1@example.com who are assigned and accepts mail from group1@example.com and group2@example.com
and as well user2@example.com who accepts also mail from group1@example.com and group3@example.com

Thank you very much for your assistance

I'd put them in the aliases file

Don't forget to run newaliases after changing the aliases file

so..i will open a new account from users and groups, then add group1: user1, user2 and run newaliases?

Does i need to activate aliases from main.cf?

Thank you

It should be there by default - have a quick look.