Port 25 won't open despite ufw allow 25

I’m trying to set up an email server. I can’t seem to get port 25 to open for me. I literally just did:

ufw disable

ufw reset

ufw default deny incoming

ufw default allow outgoing

sudo ufw allow 22/tcp

sudo ufw allow 25

And then sudo ufw status verbose…

Status: active
Logging: on (low)
Default: deny (incoming), allow (outgoing), disabled (routed)
New profiles: skip

To                         Action      From
--                         ------      ----
22/tcp                     ALLOW IN    Anywhere                  
25                         ALLOW IN    Anywhere                  
22/tcp (v6)                ALLOW IN    Anywhere (v6)             
25 (v6)                    ALLOW IN    Anywhere (v6)   

However, one cursory glance of sudo netstat -tulpn | grep LISTEN and…

tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      512/systemd-resolve 
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      664/sshd: /usr/sbin 
tcp6       0      0 :::22                   :::*                    LISTEN      664/sshd: /usr/sbin 

and telnet [my server IP] 25:

telnet: Unable to connect to remote host: Connection refused

What gives? How can I open up my ports?