Also the documentation has now been updated to
1) Point to new maintained sendmail fork.
2) Show how to use PowerShell and its Send-MailMessage cmdlet.

I believe that the sendmail still works.

Anyway, I do not understand your question. You know how to send an email with blat command from a batch file. And you have an example how to execute a command from a batch file when WinSCP succeeds or fails:
https://winscp.net/eng/docs/script_email
So you have everything you need, don't you?

I forgot to add:

I'm already able to send mail in command line with blat.
I'm only not able to use blat in WinSCP.

Hi,
I made a script to send backup from local disk to external FTP (with synchronize option)
It works perfectly.
But I would like to send an email to inform me in case of failure.

In documentation I found docs for sendmail.exe but this program has been abandoned..
I found blat but I hadn't found documentation to running blat with WinSCP.

Can you help me?
Thanks!