Some servers blacklist you even if you have DMARC, SPF, DKIM, DNS setup perfectly, but your IP is in a block of addresses that may or may not have been hosted by the same ISP of some unrelated server that was possibly compromised 10 years before you even set up the mail server. Ask me how I know.
The need to transcode has nothing to do with location. It has everything to do with the codec support on the client.