Hi again,
When they say regulations are changing every day they are not kidding😂😂..
I went back to Phuket Immigration today and an official postmarked document is no longer required. I submitted a color print of my embassy letter with my name and passport number on the bottom. I am American.
TLDR : Answer Summary
Recent changes in Phuket Immigration requirements allow American expats to submit a color print of their embassy letter, including their name and passport number, instead of an official postmarked document. This update currently applies specifically to Phuket Immigration.