I can't send email from Alias

When I send email from alias as reply-to address via the my ISP’s SMTP server, an error message is displayed. Does it mean my ISP doesn’t allow me to use alias?
My alias address is provided by a domain registration service. And an email sent to the alias address is forwarded to my ISP’s address.

eM client Pro
Version: 8.1.1054

Most email providers do not allow you to send from an email address other than the one you use to login to that server.

There are exceptions, and they usually involve enabling the alias on your email server.

Best to contact your provider and ask them for advice as they are the one blocking your outgoing message.

Hi Gary,
I got it, thanks!! I will contact my ISP.