There has been so many people complaining about not being able to
send messages with the mail() function on Windows that I decided to
investigate.

Apparently, it seems that it is not handling SMTP multi-line responses.

Multi-line responses may be returned or not depending on the vendor of the SMTP
server.  The way it works is by returning a - character right after the
response code instead of a space. When this is returned, it means that this is
not the last response line.  So, the SMTP client has to fetch the next
response line until it finds the last one that has the same response code
followed by a space.

I don't use Windows, so I did not want to fix the problem because I would
not be able to try the fix. Anyway, it seems that all the fixing that is
needed lies within the Ack() function.