What is the process for submitting a 90-day report by post in Thailand and what should I consider?

90 days report by post to CW, I get slip after 32 days from the date I sent envelope to CW. So, as Tod advised previously, there is no worry as this can take double or triple time compared to “normal” before pandemic (4-6 weeks). I also noted that delivery was signed by Security Guard, and not by CW employee as before. I assume they get mail and then deliver it to Mueang Thong Thani to processing let’s say one time per week. So if someone still prefer reporting by mail, please use EMS and keep receipt until you get slip back. QA why I use report by mail is: if report online fails for any reason (as It failed for me couple of times before) , then I must do report in person, and this will cost me taxi + time + absence from work.