Unable to send email from grafana


We have installed grafana in Azure AKS using Helm version 10.3.3. All the pods are stable and running. Able to access the grafana page successully.
Now we are unable to send the emails from grafana, we have added the required SMTP configuration in grafan.ini, Also
Uploading: Error.png…
able to telnet from AKS to SMTP server. But we are not able to trigger the alert getting authentication issue. Can you please help.
Attached the error and SMTP configuration.