How to access Exchange shared mailbox from Thunderbird, different domains

I have an email address like [email protected] and I want to access a shared mailbox [email protected], where company1 and company2 are just different names at the same server.

I use Thunderbird/Postbox client instead of Outlook due to important religious matters. And everything works fine if the shared mailbox is @company1.com. I only need to set:

User Name: [email protected]\[email protected]

However, working with company2.com like this:

User Name: [email protected]\[email protected]

does not work at all - the password is not accepted.

How can I work with Exchange's shared mailboxes if the domain names do not match?

Solution 1:

As per an answer listed on How to access a Shared Mailbox using Thunderbird or other IMAP client you may just need to define, confirm, or change a unique alias for the shared mailbox in Exchange 2016 and then use the below syntax rather than what you tried per your question.

User Name: [email protected]\sharedmailbox (user\shared mailbox alias)

How to access a Shared Mailbox using Thunderbird or other IMAP client

Exchange Configuration

USER EMAIL: [email protected]   
PASSWORD: password
SHARED MAILBOX: [email protected]      (could also be @domain.com, of course)   
SHARED MAILBOX ALIAS: shared-mailbox

Note: Please make sure to create the UNIQUE alias always with the mailbox, because it creates the user [alias]@maindomain.com. In this case [email protected]

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Settings for IMAP Configuration

EMAIL ADDRESS: [email protected] (shared mailbox)
IMAP SERVER: outlook.office365.com   
SMTP SERVER: smtp.office365.com
USERNAME: [email protected]\shared-mailbox  (user\shared mailbox alias)   
PASSWORD: password (user's password)

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SMTP Login Is Different

USERNAME: [email protected]  (users email)   
PASSWORD: password (user's password)

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