Mail sending with Business Central

Hi everyone,

One of our customers, using BC365 in the cloud, wants to send the invoices by mail directly from the webClient, but they get an error. I tried to configure the SMTP with the data provided by their system manager, but I see this error:

i get this error using the configuration of their own SMTP server, into the O365...  Using the O365 account, I get this error:

Which are the requirements to send mails from the web client?  Any type of configuration may be in the O365 account? 

Thank you very much