This is probably because the Exchange Account secret has expired.
Update Exchange Secret
You will need to get your eMail/IT provider to create a new one - they will need to go into your Azure Portal and
Click Certificates & Secrets.
Click Client secrets, then click + New Client Secret.
Enter an Exchange Sync description.
Set the Expires value to 24 months.
Click Add.
Write down the client secret value (not the Secret ID).
📌 Note: If they don't write it down now, they won't be able to view this later and will have to delete the existing client secret and add a new one.
Update Access Recruitment CRM
Your eMail/IT provider then need to give you the new client secret value which you then input into Access Recruitment CRM as described below:
Login to Access Recruitment CRM as an administrator.
Click Tools then click Integrations.
Click the Office 365 tab. If this isn't visible, select it from the More drop-down.
Enter the following values, which your IT have given you:
Enabled: ensure this is selected.
Applicant (client) Id (from Office 365 Client)
Directory (tenant) Id (from Office 365 Client)
Client Secret Value (from Office 365 Client)
📌 Note: If your client secret expires, then a new one can be added in the Azure portal