That is correct. Sending email from the Laserfiche web or Windows client does not care where your mail server is, just that you have a local mail client. The Laserfiche Office integration is similarly unaware of where your messages come from as long as they land in Outlook.

However, you need to be aware of the implications on sending emails from your automated services. See https://support.laserfiche.com/kb/1014391/deprecation-of-basic-authentication-in-exchange-online  for how Exchange Online authentication works with other applications like Forms or Workflow.