You can configure Microsoft 365 MFA account for notification settings if you want Veeam Backup & Replication to send email notifications about backup job results.
You can configure Microsoft 365 non-MFA account for notification settings if you want Veeam Backup & Replication to send email notifications about backup job results.
You can configure the SendGrid account as an SMTP relay for notification settings if you want Veeam Backup & Replication to send email notifications about backup job results.