SMTP authentication fails

The Problem

When I try to authenticate myself with an account that uses NTLM authentication, I get an error that authentication failed and check the password, however the password is correct.

Proposed Solution

I don’t know if mailspring supports NTLM, or if the error comes from another place, but every other field is correct.

Context

— Output from the logs —
SASL_PATH: /usr/share/mailspring/resources/app.asar.unpacked
SMTP Last Response Code: 250
SMTP Last Response: becas.av.it.pt Hello [172.16.10.15]
SIZE 36700160
PIPELINING
DSN
ENHANCEDSTATUSCODES
AUTH GSSAPI NTLM
8BITMIME
BINARYMIME
CHUNKING
mailsmtp Last Error Code: 296
mailsmtp Last Error Explanation: Unknown
mailsmtp Last Error Location: 10
mailsmtp Last Auth Type: 64