Hi All, a third party system is posting some info on my suitelet Endpoint which is giving 405 Method not allowed error. I tested that in APItester. The same results. Then I added User-Agent: Mozilla/5.0 in the Request Header. It works. Now the question is: I dont have control on 3rd party’s request. Is it possible to include something at my end in Suitelet to resolve this ?

I think there is nothing you can do in Suitelet. As 405 is general sever reply before your suitelet is executed. You can only ask 3rd party to add this header or check if you can add it on your own in 3rd party tool.