If desired, having one carrier would allow the maintenance of the mailbox rule (with, as discussed above, a reduction in competitive pressure), which in turn would be helpful in protecting the mail.
Having one carrier would be make protection for the mail more difficult.
mnli hypothesis: Having one carrier would be make protection for the mail more difficult. premise: If desired, having one carrier would allow the maintenance of the mailbox rule (with, as discussed above, a reduction in competitive pressure), which in turn would be helpful in protecting the mail.