Function rcpt 

pub fn rcpt(input: &[u8]) -> IResult<&[u8], Command>

rcpt = “RCPT TO:” ( “<Postmaster@” Domain “>” / “” / Forward-path ) [SP Rcpt-parameters] CRLF

Note that, in a departure from the usual rules for local-parts, the “Postmaster” string shown above is treated as case-insensitive.