I tested this program and unfortunately it did not always work correctly with a proxy.
I raised my proxies with an open port and she refused to send.
Tech support said it resolved the issue.
You need proxy socks with open port 25. Option A: parse with google socks5 and check the port (in this option, not all mail providers will accept mail) and messages will also end up in the spam folder.
You can buy on hotsox.ru but again, the inbox is not guaranteed.
Inbox can be reached if there is a ptr record, dns manager has dmarc,spf,dkim and the letter must be signed by dkim. this can be done using either your own proxies or raise your own mail server.
you can also buy a proxy with an open port 25 here.
https://remproxy.com/
But due to recent events, you may not even be able to pay.
Proxy mailing is best done to corporate addresses.