SMTP Error invalid certificate

Have a look at this link, which explains how to set it up
The section:
Option 2: Send mail directly from your printer or application to Office 365 (direct send)

https://docs.microsoft.com/en-us/Exchange/mail-flow-best-practices/how-to-set-up-a-multifunction-device-or-application-to-send-email-using-office-3?redirectSourcePath=%252fen-us%252farticle%252fHow-to-set-up-a-multifunction-device-or-application-to-send-email-using-Office-365-69f58e99-c550-4274-ad18-c805d654b4c4

So the setup should be
server/smart host is Your MX endpoint, for example, contoso-com.mail.protection.outlook.com
Port Port 25
TLS/StartTLS Enabled
Email address Any email address for one of your Office 365 accepted domains. This email address does not need to have a mailbox.

I hope this helps.

Hi,

Well, yes it is possible.
For example you want to setup NAV to send emails to company ABC.
You have to use the SMTP details from the company that has Office 365 and NAV.
With that setup NAV will connect to SMTP Server and send the email to company ABC or any other user.

The reason for this is spam emails.By providing the SMTP address e.g.
contoso-com.mail.protection.outlook.com
it knows it is not relaying spam emails.

For example, if clients do not have SMTP then I use my details, (we are partner with Office 365) and this works fine.