FYI I just went to Udon Immigration with a COVID letter from U.S. Embassy via email (also printed it out in color) and they said it had to be an original document via post mail lol... I asked the U.S. Embassy but no reply yet, I doubt they will offer that. Police were grumpy today and I pushed a few times to be sure... not sure if their excuse is accurate or just bullshit trying to delay dealing with these.
Update: U.S. Embassy replied to me and were surprised, and said Thai Immigration offices are supposed to accept the digital/printout versions of letters.
TLDR : Answer Summary
The post discusses an individual's frustrating experience at Udon Immigration when they were informed that a COVID letter from the U.S. Embassy, even when printed in color, needed to be an original document sent via postal mail. After reaching out to the U.S. Embassy, they received information indicating that digital or printed versions should be accepted, revealing inconsistencies in how immigration offices operate in Thailand. The comments reflect various similar experiences and frustrations among expats regarding varying immigration requirements.