Scaleway block outgoing SMTP connections, it’s in their FAQ:
https://www.scaleway.com/faq/server/network/
I cannot send any email.
To avoid spam, remote mail ports (25, 465, 587) cannot be reached from our infrastructure. If you need to open the mail ports to send e-mail, you can go to the advanced options section of your server and change the security group configuration:
- On the left panel of the Control Panel, click on “Security”
- Select the Security group you want to unblock remote mail ports
- Set “Block SMTP” to No.
- Reboot your server from the control panel to apply the changes
You could also as an alternative change the SMTP port number to 2525
as SparkPost support this port.