We ship a large amount of products as first class mail letter. As you know, USPS does not offer tracking on letters (similar to how you might mail a friend a letter with a regular old envelope+stamp).
When processing these letter shipments, SS automatically uploads the "receipt number" to amazon as marks it as shipped. The problem with this, is that the customer does not realize the item is a letter, and the tracking number seems invalid (because it is not really a tracking number).
Further, amazon's system automatically checks for invalid tracking numbers, and is now sending us emails stating that if we fall below 95% valid tracking they will suspend us from listing in a specific category.
I've already discussed the situation with Amazon, and they say that shipping small and low value items without tracking is within policy, and they're fine with that. What they are not fine with is the invalid tracking.
So, my question is, is it possible to NOT upload non-trackable numbers for first class mail shipments? I'd still like the orders marked as shipped, but without the tracking number field being populated.
I've checked the forums for some answer to this, but the closest I found was similar question regarding international letters. I found that setting "Send non-trackable Tracking Numbers to Marketplaces", but this only applies to international shipments. Is there some similar setting for domestic letters?