SMTP server not working from external device.

I currently have a server at OVH, they swear that port 25 is not blocked and I followed https://www.howtoforge.com/tutorial...l-pureftpd-bind-postfix-doveot-and-ispconfig/ to configure the server.

I can send email using the Webmail client with no issue however when I connect my android phone I can receive but not send.

Not sure what to do.

 

And TLS encryption.
That's how it works for me.

 

Did you use your local wlan with android? Some routers blocking port 25 for "security" reasons.