@Bunnz said in "proxy handshake error"/"Failure when receiving data from the peer" when using proxy with Mail Module:
And proxy is working in HTTP request just fine
email ports are disallowed for these proxies.
What's with all these errors in 28.9.3 
Getting tons of these errors on all sorts of proxies (mobile/ residential) from different providers.
The same proxies work very well in normal browsers, antidetect browsers, even in automation tools like the BAS competitor that we all know
LE: When the proxy is set, the HTTP sniffer gives these errors:

