I’m not sure what version of the update broke my mailer but it was probably 3.5.x. I had a similar issue with my database connections that @teodor fixed right away and wondering if this is the same kind of issue?
in the lib/mail/mailer.asp file
"006~ASP 0174~Invalid Path Character(s)~An invalid ‘/’ or ‘’ was found in the Path parameter for the MapPath method.
I’m now currently on 3.5.4. I deleted the mail.asp and also the mailer.asp files and it recreated them and made sure I uploaded them to the server.