Yes... or so one would think, Chris. However, there is something else going on here.
This setup that I have has been working for well over a decade, (probably closer to 2), with zoneedit with minor variations over time. Yet, despite various attempts no E-mail ever reaches my server using any variation of the following, including trying different ports. (My ISP blocked port 25 around the end of last year.) No logs show rejection, connection, errors or warnings that anything E-mail related on any port, has been pointed at my machine(s).
| MX records |   | 
| 
| MAIL FOR ZONE | MAIL SERVER | PREF | TTL |  | self-wrighting.net | self-wrighting.net:26 | 5 | default | 
 |  | 
 
My setup is not complex and postfix here can be reached from the outside, via any port that I choose, (save port 25), the current one in use being port 26.
Any MX test site can reach my E-mail server on any port that I set it too, and receives the appropriate responses. However, still no E-mail reaches my server. The only thing outside of my control that appears to not be working is the routing of E-mail via your servers to mine.
Has something in your setup or process changed since last December that I am not aware of that can affect this?
MXToolbox shows this when doing an MXLookup on 
self-wrighting.net:
mx:self-wrighting.net
      
|  | Test | Result |  |  |  |  |  | 
|---|
|  | DMARC Record Published | No DMARC Record found |  More Info |  | DMARC Policy Not Enabled | DMARC Quarantine/Reject policy not enabled |  More Info | 
|  | DNS Record Published | DNS Record found |  |  |  |  |  | 
 
Yet, when preforming 
Test Mail Server for 
self-wrighting.net results show;
smtp:self-wrighting.net   
Unable to connect after 15 seconds.
  
|  | Test | Result |  | 
|---|
|  | SMTP Connect | Failed To Connect |  More Info | 
| Session Transcript: Connecting to 76.11.87.209
 2/26/2023 6:24:30 AM Connection attempt #1 - Unable to connect after 15 seconds. [15.01 sec]
 
 LookupServer 15034ms
 |  |  |  | 
 
Which is EXACTLY what one would expect if zoneedit was routing to port 25 and 
not to the one selected which is right now, set to port 26.
However, setting the 
Test Mail Server to 
self-wrighting.net:26 works exactly as expected; complete success.
smtp:self-wrighting.net:26   
220 mail.self-wrighting.net ESMTP Postfix
              
|  | Test | Result |  | 
|---|
|  | SMTP Banner Check | Reverse DNS does not match SMTP Banner |  More Info | 
|  | SMTP Reverse DNS Mismatch | OK - 76.11.87.209 resolves to host-76-11-87-209.public.eastlink.ca |  | 
|  | SMTP Valid Hostname | OK - Reverse DNS is a valid Hostname |  | 
|  | SMTP TLS | OK - Supports TLS. |  | 
|  | SMTP Connection Time | 1.113 seconds - Good on Connection time |  | 
|  | SMTP Open Relay | OK - Not an open relay. |  | 
|  | SMTP Transaction Time | 1.722 seconds - Good on Transaction Time |  | 
| Session Transcript: Connecting to 76.11.87.209
 
 220 mail.self-wrighting.net ESMTP Postfix (Ubuntu) [1035 ms]
 EHLO keeper-us-east-1d.mxtoolbox.com
 250-mail.self-wrighting.net
 250-PIPELINING
 250-SIZE 52428800
 250-ETRN
 250-STARTTLS
 250-AUTH PLAIN
 250-ENHANCEDSTATUSCODES
 250-8BITMIME
 250-DSN
 250-SMTPUTF8
 250 CHUNKING [188 ms]
 MAIL FROM:<supertool@mxtoolboxsmtpdiag.com>
 250 2.1.0 Ok [186 ms]
 RCPT TO:<test@mxtoolboxsmtpdiag.com>
 454 4.7.1 <test@mxtoolboxsmtpdiag.com>: Relay access denied [179 ms]
 
 LookupServer 2298ms
 |  |  |  | 
 
Are you SURE that your setup is routing to the port set on my Account setup page as shown above?