When it comes to SMTP Settings in eFileCabinet Online and SecureDrawer, it is required that actual SMTP settings are used, not exchange server settings. Exchange servers will not work, as exchange servers are set (for security reasons) to reject mail requests that originate from outside of the LAN environment (meaning anything not local to the network will be rejected).
One option from this point is to contact your email provider and have a dedicated SMTP server set up so that the messages from SecureDrawer can be relayed.
Alternately, you can request that the company who provides your domain set up another mail server under their domain that is outside of your office.
Should you choose to use email providers like Gmail, Yahoo, etc. you can set up your emails to reflect your company (firstname.lastname@example.org, for example), and the SMTP settings that follow are fairly simple (smtp.gmail.com for Gmail, smtp.yahoo.com for Yahoo, etc.)