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OSX Mail is the same as any other email client .. if you open the Activity Window (located in the Window Menu) you can see what Apple Mail is trying to do. &nbsp; It might highlight what mail and protocol it is using.<br />
Did you open port 25 for SMTP or 110 for POP mail?<br />
<br />
If you open a Terminal window and type <br />

<pre><code id="code-20-37732406-1">lsof -i -P</code></pre>
This will show you all the ports which are in use... in there you'll see Mail and you can see what ports it has open.
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OSX Mail is the same as any other email client .. if you open the Activity Window (located in the Window Menu) you can see what Apple Mail is trying to do.   It might highlight what mail and protocol it is using.
Did you open port 25 for SMTP or 110 for POP mail?

If you open a Terminal window and type


lsof -i -P

This will show you all the ports which are in use... in there you'll see Mail and you can see what ports it has open.

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sorry guys, it was some other problem which I can't explain.
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sorry guys, it was some other problem which I can't explain.

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I'm having trouble to open ports on our wireless firewall for Mac Os mail user. <br />
When I open all services, it works, but doesn't when I open only &nbsp;80, 143, 587. No SSL is required. I checked the Mail preference in Mac Os Mail, those are the ports shown at exchange setup required. What else do I have to open?
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I'm having trouble to open ports on our wireless firewall for Mac Os mail user. 
When I open all services, it works, but doesn't when I open only  80, 143, 587. No SSL is required. I checked the Mail preference in Mac Os Mail, those are the ports shown at exchange setup required. What else do I have to open?

Opening firewall for Mac OS Mail

Apple's early computers ran on a variety of operating systems, including a Pascal version and one based on CP/M, before releasing its ProDOS with the advent of its 16-bit computer. With the release of the Lisa, which had its own OS, Apple and computing entered the graphical age; it was followed by the Macintosh, which offered a series of "System" operating systems. Other Mac operating systems included PowerPC until Apple acquired NeXT and folded it into the Mac OS. Current operating systems for Apple devices are Mac OS-X and iOS.

Apple OS

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.

Email Servers

Hardware-based firewalls provide more sophisticated protection for inbound and outbound traffic than the simple Windows software firewall or the basic NAT firewalls found in routers. These devices implement techniques such as stateful packet inspection, deep packet inspection, and content filtering; and may include built-in antivirus and anti-malware protection.