authentication failed: another step is needed in authentication

[xuqplus]

hello, i started the container with command docker run -it --rm -p 25:25 -e maildomain=xjplus.xyz -e smtp_user=test123:test123 --name tmpp catatnight/postfix,
then test it with telnet as below and i got authentication failure, what's wrong with that?
isn't sasl used at auth login? look for help, 3q..

[C:\~]$ telnet xjplus.xyz 25
Host 'xjplus.xyz' resolved to 106.12.80.76.
Connecting to 106.12.80.76:25...
Connection established.
To escape to local shell, press 'Ctrl+Alt+]'.
220 xjplus.xyz ESMTP Postfix (Ubuntu)
helo xjplus.xyz
250 xjplus.xyz
auth login
334 VXNlcm5hbWU6
test123
535 5.7.8 Error: authentication failed: another step is needed in authentication
auth login
334 VXNlcm5hbWU6
test
334 UGFzc3dvcmQ6
test
535 5.7.8 Error: authentication failed: authentication failure
quit221 2.0.0 Bye
Connection closing...Socket close.
Connection closed by foreign host.

[dudz94]

You have to put your login and password encoded in base64.