Nothing has been announced, but if past practice holds, a stamped flat-rate envelopes featuring the same design as the new Priority Mail stamp will be issued for this rate on Sunday, January 24, 2021, the date the rate goes into effect. There will not be a first day ceremony and in-person cancellations will be hard to obtain.
Updated January 6th:
The Virtual Stamp Club has confirmed this issue. The item numbers are:
- 233205 Packet of 5
- 233210 Packet of 10
- 233225 Packet of 25
- 233216 First Day Cover Cancelled envelope
If you want a Single Pre-Paid Envelope from this issue: Postmaster Oneco CT 06373 Mail-Orders Only ( No Internet/Telephone ) Check/M.O. payable to Postmaster Oneco CT $7.95 each No S/H fees – sent to You via Priority Mail .
envelope size?
The “standard” 9×12 size.
https://store.usps.com/store/product/stamp-collectors/castillo-de-san-marcos-prepaid-flat-rate-envelope-first-day-cover-S_233216
Flat Rate Envelope