We have linked the domain of our company to Google Apps and we also have a Kerio Connect (mail server) installed in our company which uses Google as SMTP relay. As google requires SMTP authentication we use one of our mail addresses for authentication. But it causes google to substitute "From" header with the address of the user used for authentication.
For example, we want to send email from email@example.com. User firstname.lastname@example.org is used for SMTP authentication in SMTP Relay settings of Kerio Connect mail server. The mail gets delivered, but on recipient side it says that the message is from email@example.com, though it was actually sent from firstname.lastname@example.org (Reply-to header is also set to email@example.com :( ).
In the "Sending mail from a different address" section of Gmail help there is an explanation of how I can send email from, say, firstname.lastname@example.org when email@example.com is used for authentication. - They say I need to sign up to Gmail with user2@ and add user1@ as another mail address I own (Mail settings -> Accounts -> "Send mail as" section). And it works. For example, when I sign up with firstname.lastname@example.org and add email@example.com as another mail address I own, then I can send email from firstname.lastname@example.org using email@example.com for authentication, and the recipient will see that the message is sent from firstname.lastname@example.org.
But what if I have a hundred of email addresses on the domain? I don't want to add those 100 addresses in the settings.
I just want that any user (*@company.org) could send email using email@example.com user for authentication and I want recipient to see that the message is sent from *@company.org, not firstname.lastname@example.org.
Is there an easy way to do that?