Why can't postal ems intercept it?

Unable to intercept for the following reasons:

1. Postal ems has arrived in the local area and cannot be intercepted.

2. Postal ems cannot be intercepted due to network reasons.

3. Without an effective interception system, postal ems interception can only be done by telephone or contact with the courier after the mail arrives at the delivery office, which leads to low success rate and high communication cost, resulting in interception failure.