[quote user="matthewsdowns"]It seems like my ISP (Verizon) has blocked the ability to open port 25 in my residential use?  Is there a work-around using a different port or something else I can do?[/quote]

Checkout the services provided by DynDNS.  They provide services for both inbound and outbound mail on non-standard ports for a pretty reasonable annual fee.  https://www.dyndns.com/services/

I'm having trouble receiving mail from outside servers in my mercury system.  I can send between local users fine, and from the local users to outside domains (gmail), but cannot send from gmail back into the mercury accounts.  No error messages show up, the mail just seems to disappear.  I'm using verizon fios as my internet connection and their router.  I think my problem has to do with the IP address that I'm using in my settings, not sure if it's the correct one, but it must be if I can send mail out, right?

Any help is appreciated. Thanks!

You give us very little to work on, but here's a list of things for you to check:

- did you open port 25 on your router/firewall? 

- did you redirect port 25 from your router/firewall to the Mercury server? 

- did you make sure there is no local firewall on the Mercury server blocking port 25?

- do you have a static IP address?

- do you have correct MX records for your domain?

/Rolf 

It seems like my ISP (Verizon) has blocked the ability to open port 25 in my residential use?  Is there a work-around using a different port or something else I can do?

Many Internet providers block outgoing traffic on port 25 for domestic clients to prevent spamming. There seems to be little reason to block incoming traffic, though, but I guess they did that as a bonus...

The SMTP protocol requires the server to answer on port 25, there is no way to change that in MX records or otherwise. So you would need to direct incoming messages for the domain to another server with no restrictions for port 25. It could then either relay the messages to you on another port (2525 perhaps) if such a service is available, or save them in a domain mailbox so you can collect them with MercuryD.

/Rolf