Trying the same username and password over the smtp service using hydra's "smtp-auth" module.
My understanding was hydra can try dictionary attack over an smtp service which uses NTLM hashing, my enumerationg results over the listening smtp confirms that it uses NTLM authen type.
Yet using Hydra gives me the following results:
command: hydra -l username -p password(text) -o output.txt -v -V xxx.xxx.xxx.xxx
Output Error: SMTP AUTH LOGIN error: 504 5.7.4 unrecognized authentication type