Sending of the message failed/The message could not be sent because
from HTYP, the free directory anyone can edit if they can prove to me that they're not a spambot
- Full message: Sending of the message failed. [newline] The message could not be sent because the connection to Outgoing server (SMTP) <domain name> was lost in the middle of the transaction. Try again.
This appears to result from the server closing the connection immediately upon establishing it:
woozle@SamEagle:~$ telnet hypertwins.org 465 Trying 18.104.22.168... Connected to hypertwins.org. Escape character is '^]'. Connection closed by foreign host.
There might be no perceptible delay between the "Escape character" message and the "Connection closed by foreign nost" message.