What are these strange codes - e.g ebayc4jxndw - that have begun appearing in delivery addresses?

[helenhappenstance]

What are these strange codes - e.g ebayc4jxndw - that have begun appearing in delivery addresses? They have to be removed individually, or otherwise would presumably cause postal deliverers unnecessary confusion.

[**peaseblossom**]

Here's info about it:

https://community.ebay.co.uk/t5/Announcements/Royal-Mail-tracking-and-delivery-events-on-eBay-from-1...

It says "The unique eBay code will not be printed as part of the address on the postage label."  Unless of course you don't use ebay labels.