Why can't I send email
If you're able to receive emails but are experiencing issues sending email when using an email client such as Thunderbird, Outlook, or etc., the issue may be caused by your ISP (Internet Service Provider) blocking the outgoing (SMTP) port 25.
This has become a very common practice nowadays from ISPs as spam has only become an even bigger growing concern. ISPs block port 25 for all servers except for their own in an effort to direct all mail their subscribers send through their mail servers. This way they can monitor all mail that they are responsible for and take any necessary action.
All of Acenet's shared servers are configured to use port 587 for outgoing email as well. You can change the settings of your outgoing (SMTP) port within your email client by going to the email account properties, and selecting the Advanced or SMTP tab. Change the outgoing (SMTP) port from 25 to 587, and please try to send once more.
If you have a virtual or dedicated server running cPanel, you can configure another port for outgoing email through your server's WHM (Web Host Manager). You can view more details on how to do so here: