Thanks for your answer and sorry for the late reply.
During the last days I had no time to try your suggestion.
Finally I followed your advice.
At the end I did the following
–> Created the user firstname.lastname@example.org
–> Logged in with email@example.com @SOGo web interface
–> Set-up a delegation for firstname.lastname@example.org
–> Shared the folder “Inbox” with the user email@example.com
–> In the admin settings of the firstname.lastname@example.org Mailbox I had to select the info@company address at the “Allow to send as” setting. Otherwise user1@ couldn’t send mails with the from address info@
This seem to be quite a lot of things to set, so that a user1@ can see the mailbox of user info@ and to be able to send mails in the name of info@.
And still, I cannot share the whole mailbox along with all its folders with another user. If I share the folder “Inbox”, the other user can still not see the “Sent” folder and all the other folders of that mailbox.
Did I follow your suggestion correctly?
Isn’t there a way to let a user1@ login with the username info@, but the password of user1@?
I think that would be the cleanest way to share the info@ mailbox without giving away the password of info@.
Because if a user leaves the company, you don’t need to change the password of info@ and tell all the remaining users the new password.
Maybe there is a way to tell Dovecot, that the email@example.com mailbox may accept all passwords of @company.com users.