Hi there, @Christophe.

I understand your concern about your accountant not receiving an invitation to QuickBooks Online (QBO). 

My colleague has provided some steps to resolve the issue, if you haven't performed it yet I highly suggest following them if you haven't already done so.

Furthermore, there are several reasons why invited users may not receive their email invitations. To assist you with this, I recommend taking a look at the sample listed below:

• The invitation might be in their junk or spam folder.
• The company’s email address is incorrectly formatted in the Company tab under Account and settings.
• The recipient’s mail servers might be blocking the email.
• The invitation may have already expired. Email invites expire 48 hours after they are sent.

As my colleague says, if an invitation is almost or more than 30 days old, it's recommended that clients delete the original invite instead of resending it. To ensure that your workflow continues without any hassle, you can send another invitation email. Let me walk you through how:

Step 1: Check if your email address is correct.

1. Go to Settings, then select Account and settings.
2. Select the Company tab.
3. In the Contact info section, select Edit ✎.
4. Even if it looks correct, carefully re-enter the company email address. Be sure not to use any extra characters or leave any blank spaces before, within, or after the address.
5. Select Save, then Done.

Step 2: Make sure the email recipient has an Intuit Account

If the user doesn’t already have an Intuit Account, they should create an account with their desired email address. Having an Intuit Account may help prevent the user invite email from getting flagged as spam.

Step 3: Resend the user invite.

1. Go to Settings ⚙.
2. Select Manage Users.
3. Find the user you need to invite again.
4. Select Resend Invite in the Action column.

Note: If you don't see the option to resend and the status shows Active, it means the user has accepted your invitation to join your company and has already set up a login. They can now sign in to qbo.intuit.com and start working on your QuickBooks company.

Moreover, if the issue persists and you or your accountant encounter a specific error message during the invite process, please kindly give us additional information about it. This will enable us to investigate further and provide a solution.

Additionally, here are some articles that you can read to learn how to add, manage, or delete user profiles in QuickBooks Online: Add and manage users in QuickBooks Online

If there's anything else you need to accomplish in connecting with your accountant, please let me know by leaving a comment below. I'd be more than happy to work with you. Keep Safe!