Well, to just get the message and email address in a naive way you could do (untested)

my ($message,$email)=m{^-S\s* "([^"]*)" \s* (.*)}x;
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BUT this way you don't allow any escaped " in your message string. i.e. something like "hi, that \" char is difficult". If you change [^"]* to .* then it would allow escaped ", but then you would get into trouble if the email address had any " char in it, for example "John Doe" <doe@wo.com>.

Also note there is no real checking if the email address comforms to any email address standard. If you only expect doe@wo.com style addresses, that could be parsed with something like [^@]+@[^@]+, but to parse any valid email address you should use a module like Mail::Address.

If you get this line from unknown sources, there are more things to consider, depending on what you want to do

And the hoped for output is?

Please see, How (Not) To Ask A Question for some hints on how to write a question that will be effective in getting you the help you need.

Best, beth

Regular expression for what????

Complete your question. Refer How do I post a question effectively?