Hi @michel 

Check whether this content is use full to you.
 

• When setting up the Mail_Sender, you need to set the "Security_Protocol" value as "SMTP + STARTTLS".
• This protocol was introduced via the solution 264861 to solve the issue with SMTP host while using "smtp.office365.com" as the Host Name.
   

How to setup Office 365 supported Mail_Sender configuration in APP10? | IFS Community


Thanks & Regards
Shan

@Shan Peiris 

thank for your quick reply，

the customer doesn't use the office365 mail server.

if I changed the sercisty_protocol as smtp+starttls

error as