Plain login throwing "Unsupported Authentication Type"

[AvrumFeldman]

I'm trying to intercept a email to see the sender and recipient, but the application is throwing an error that the authentication type is unsupported, even though it's using plain login.

Command used to start the application

sudo MITMsmtp --server_address 192.168.4.178 --port 587 --print-lines

See console output

Waiting for messages

[New connection from 192.168.4.16]
S:220 smtp.example.com Simple Mail Transfer Service Ready
C:EHLO <>
S:250-smtp.example.com Hello <>
S:250-SIZE 1000000
S:250 AUTH PLAIN LOGIN
C:
Closed connection!
----------------------------------------
Exception occurred during processing of request from ('192.168.4.16', 60137)
Traceback (most recent call last):
  File "/usr/lib/python3.12/socketserver.py", line 692, in process_request_thread
    self.finish_request(request, client_address)
  File "/usr/lib/python3.12/socketserver.py", line 362, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/lib/python3.12/socketserver.py", line 761, in __init__
    self.handle()
  File "/usr/local/lib/python3.12/dist-packages/MITMsmtp-0.0.3.dev0-py3.12.egg/MITMsmtp/SMTPHandler.py", line 65, in handle
    raise e
  File "/usr/local/lib/python3.12/dist-packages/MITMsmtp-0.0.3.dev0-py3.12.egg/MITMsmtp/SMTPHandler.py", line 55, in handle
    self.readAuth()
  File "/usr/local/lib/python3.12/dist-packages/MITMsmtp-0.0.3.dev0-py3.12.egg/MITMsmtp/SMTPHandler.py", line 132, in readAuth
    raise ValueError("Unsupported Authentication Type requested by client: " + line)
ValueError: Unsupported Authentication Type requested by client:
----------------------------------------