"Can I run my Mail-in-a-Box at home? No. "
More like “Should I run my Mail-in-a-Box at home? No.” Still get marked as spam by gmail. rDNS is a killer
But can get a negative score from Spam Assassin on dkimvalidator.com
I made some notes, mainly for myself, but wrote it up in case it helps anyone else. The server is Ubuntu 18.04 running LXC (Linux Containers). A virtualization method for running multiple isolated Linux systems (containers) on a control host using a single Linux kernel. My home router has a single IP address, with alas rDNS (reverse DNS resolution) not controlled by myself. My iSP does not block ports.
Thanks for the project,
I can help you solve that with an inexpensive SMTP relay service. PM me if interested.
I have Charter/Spectrum residential service.
They do not block the port, but they do flag their whole Domain range as being SPAM. This basically yields the same result.
On a more technical level, that IP range is classified as ‘residential’ … which basically leads to the same thing.
In my region Charter (now Spectrum) offered business plans for the same price as residential, so I could get the business IP address (not blacklisted) and rDNS.
Residential IP address ranges are most often allocated using DHCP rather than being given as static addresses. In some cases due to the nature of the network these addresses may persist for months or years, but are still liable to change in certain circumstances.
Because of this it’s not recommended to run a mail server on a home address although it is possible.
There are several blacklists that list IP ranges allocated via DHCP because of this. Inbound mail servers may choose to either raise the spam score of mail coming from such connections, or even reject the mail altogether.