Hi Kumar
,
I just opened your query..
You can use openSSL for retrieving the certificates.. In openSSL type in the below
s_client -connect smtp.office365.com:587 -starttls smtp
You will get BEGIN CERTIFICATE and END CERTIFICATE tags..Copy all the text including the tags to a text file. Then we will rename the file to a .cer file.. Now import this in your SMTP XS tool
-Avinash