Allow empty protocols line when using --exec-mail.
Allow empty protocols line when using --exec-mail.

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jwm/dovecot-notmuch,jwm/dovecot-notmuch,dscho/dovecot,dscho/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch,dscho/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch,dscho/dovecot,dscho/dovecot,jkerihuel/dovecot,jkerihuel/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch