Mailbox access for external

Occasional Contributor

Hello Community,


I am working with Office365 for a short time now and I am learning by doing.

I got the request to create two mailadresses with a few conditions and I am struggeling to find the correct type of mailbox and features required for this.


The conditions are:

1. Each Mail-Adress has to be redirected to another mail adress.

Example: Adress A ->
               Adress B ->


2. After they received the forwarded mail in their personal mailbox, they want to be able to answer to that mail in the name of the original mail adress.

Example: "Name1" receives a redirected mail in his personal mailbox which was adressed to "Adress A". He answers to that mail and for the recepient it looks like the mail was sent from "Adress A".


3. They dont want to setup the mailbox in their outlook to avoid to many mailboxes in the application.


I tried already a bit and I made it work for the internal colleague. I simply created an "active user" in Office365 with the correct name, forwarding every mail to "Name1" and giving that user the reight to "send as" (Or however that translates to english). This will not work with the external colleague as I can only select O365-Users for the acces and the "send as" feature.


Any kind of advise and help is appreciated. I am wondering if there is a solution for this without creating an active user for every group mailbox I want to create. (info@company... / sales@company.... / etc.)




4 Replies

@Florian Maaß I would probably use a "Mail Contact" for creating an address in your tenant that was pointed to the External e-mail.  You could also use Alias on existing accounts and then Rules to direct the messages where you wanted.

You can do both of these in the ECP or your tenant.

Replace with your own.

A Mail User account may also work but requires a little more preparation.


The only way the Send AS feature is going to work is to have a Shared Mailbox and give that person the correct permission. 

A little trick I have learned to not have all the Shared Mailboxes show in the User Outlook Nav Tree is to use a group to assign that Send As permission on the Shared Mailbox.  Even if that person sending the mail is the only one in the group.  This way the Outlook client recognizes the permission but does not force it to appear in the user Outlook Nav Tree.

@Forrest Hoffman Thanks  a lot for the answer. I will see what I can do with the provided information.


Edit: I just noticed that I cannot access the link you posted. It requires a login and my account doesn't seem to work here. Can you provide the information in that link any other way.

@Florian Maaß  did you replace the with your tenant?  The link I provided should take you directly to the Exchange Online administration portal.

Please copy the link to a text editor and then modify to reflect your Office365 tenant and then you can copy and paste the updated URL into your browser address bar.

You can get to the same place via your Office 365 Admin Portal and then clicking Show More, and then Exchange


@Forrest Hoffman 

Well this is kinda embarassing.

Thanks again!