Since smtp servers were/are not fully working since yesterday and I started new development, I'm trying SMTP using swaks to track issues faster.
=== Trying smtp.zoho.eu:587...
=== Connected to smtp.zoho.eu.
<- 220 mx.zoho.eu SMTP Server ready June 25, 2021 10:52:38 AM CEST
-> EHLO pop-os.localdomain
<- 250-mx.zoho.eu Hello pop-os.localdomain (myIP)
<- 250-STARTTLS
<- 250 SIZE 53477376
-> STARTTLS
<- 220 Ready to start TLS.
=== TLS started with cipher TLSv1.2:ECDHE-RSA-AES256-SHA:256
=== TLS no local certificate set
=== TLS peer DN="/CN=
*.zoho.eu"
~> EHLO pop-os.localdomain
<~ 250-mx.zoho.eu Hello pop-os.localdomain (myIP)
<~ 250-AUTH LOGIN PLAIN
<~ 250 SIZE 53477376
~> AUTH LOGIN
<~ 334 VXNlcs5hbU6
~> Y29udGFfEByZWFsaXaXMuY29t
<~ 334 UGtzc3dvcQ6
~> UGFzbd91c3NSE=
<~
* 535 Authentication Failed
*** No authentication type succeeded
~> QUIT
<~ 221 mx.zoho.eu closing connection
=== Connection closed with remote host.
Ultimately, I need the other generated specific password to work for a local server I'm testing. It never worked so far (not sure if it's because of the smtp server issue or my server settings).