The bare postmaster address is case-insensitive
The bare postmaster address is case-insensitive

Per rfc2821, sec 4.5.1 and rfc5321, sec 4.5.1.

Signed-off-by: Pedro Melo <3e267facec158a22a232125c74f1f09bceb68aac@simplicidade.org>

sieutruc/qpsmtpd,salvis/qpsmtpd,smtpd/qpsmtpd,priyadi/qpsmtpd,smtpd/qpsmtpd,sieutruc/qpsmtpd,msimerson/qpsmtpd,sieutruc/qpsmtpd,priyadi/qpsmtpd,msimerson/qpsmtpd,priyadi/qpsmtpd,salvis/qpsmtpd