Getting SMTP 504 .5.7.4 "Unrecognized authentication type" trying to send a mail with Outlook 365

Question

I am trying to setup the ability to send emails using my Office365 email account from my .net site. Before i code this, i want to make sure its possible to do so and hence using a SMTP debugging tool i got from the internet. I keep getting 504 5.7.4 Unrecognized authentication type error.

Settings:

server: smtp.office365.com
Port: 587
User: [email protected]
Pass: mypassword
Requited Authentication: true
From Email: [email protected]
To Email: User: [email protected]

When i post this request i get the following logs:

Connecting to mail server.
Connected.
220 abc.outlook.office365.com Microsoft ESMTP MAIL Service ready at Sat, 15 May 2021 19:22:41 +0000
EHLO EC2AMAZ-GODJD
250-abc.outlook.office365.com Hello [1.1.1.1]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
AUTH LOGIN
504 5.7.4 Unrecognized authentication type [abc.prod.exchangelabs.com]
Forcing disconnection from SMTP server.
QUIT
221 2.0.0 Service closing transmission channel
Disconnected.

What i have tried I read that outlook has "Security Defaults" that blocks SMTP. I have turned this off.

What might be going wrong?

Answer 1

I have ran into this problem in the past. What l did back then was to enable STARTTLS, and declare the authentication will be sent in plain text.

Let me know if it works.