Many local ISPs started blocking port 25 recently. My clients can no longer access their email accounts on their email server from external clients like Outlook, etc.
I am a complete rookie in this area and I read that port 587 would work as a replacement port. Before I change the port in the server I would like to know if this is a standard widely used port and if anyone has any stories about emails not arriving at an email server whose SMTP port is 587.
I would also like to know if there are any alternatives to changing the port.