What do you have set for your HOSTNAME in SmarterMail under SETTINGS > GENERAL?

The error that you are getting when delivering email to Outlook.com and any MS Exchange Mail Servers is almost definitely due to a bad EHLO. It is possible that you have an invalid character in your Hostname that does not belong, or a <CR> or <LF> or other hidden text the could have been included with a COPY+PASTE. You would want to make sure that your Hostname is set to a FQDN (Fully Qualified Domain Name), such as mail.mydomain.tld and that there are no trailing spaces.

(Also, on the remote off-chance, does your Hostname contain the string MTRK? This could also cause a Bad ENVID when delivering email to Outlook.com and MS Exchange Mail Servers, as this is reserved by RFC 3885 for Message Tracking, which is pretty much used only by MS Exchange and Outlook.com)

Hi Scarab ,

thanks for your contribution.

The hostname is set correctly with FQDN and not contain the string 'MTRK' . 

it seems and I say it seems that the problem is linked to confirmations of delivery in outlook. Without that, no errors appear.

Simone Schilirò