Blocking port 25 on Fiber connections

Internet access discussion, including Fusion, IP Broadband, and Gigabit Fiber!
14 posts Page 2 of 2
by ewhac » Mon Nov 11, 2019 10:59 am
Sorry; should have been more clear:

sysops wrote:
Fusion DSL with static IP should not have port 25 being blocked in either direction.

Correct; it doesn't. My SMTP server works fine. The discussion is that, if I move from Fusion DSL to gigabit fiber, not only will I lose static IP, I will also have port 25 blocked. The loss of static IP can sort-of kind-of be mitigated with dynamic DNS and a cooperative DNS host (such as Pair Domains). Port 25 blocking is rather more difficult to ignore.

The main thrust of my previous lament (okay, rant) was that I appreciate that there are likely business concerns that have prevented Sonic from making static IP and IPv6 available on fiber, but that these concerns have never been even obliquely articulated, and it's the lack of information on this point that's causing whiny grey-beards like me to perennially grouse in the fora.
by quasar » Thu Nov 21, 2019 2:53 pm
I just park my real mail server on a VPS and have my local systems use opensmtpd to relay mail through it with authentication since the dynamic IP precludes regular unauthed SMTP relay whitelisting configuration.
Something like this: ... Relay.html
by ewhac » Sun Nov 22, 2020 12:45 am

So, couple of things. First: a year ago I wrote:
...I appreciate that there are likely business concerns that have prevented Sonic from making static IP [ ... ] available on fiber, but that these concerns have never been even obliquely articulated, [ ... ]

Mr. Jasper has since furnished a reason I'm satisfied with: viewtopic.php?f=10&t=16612&p=55645&hilit=static#p55645

Second, on the point of blocking port 25 (SMTP): Based on the discussion, I had assumed both inbound and outbound connections to port 25 were blocked. Evidently this isn't so:

Code: Select all

$ telnet 135.180.XX.XX smtp
Trying 135.180.XX.XX...
Connected to 135.180.XX.XX.
Escape character is '^]'.
220 ESMTP Postfix (Notice: Relaying prohibited.  Unauthorized relay attempts constitute theft of service and will be logged.)
221 2.0.0 Bye
Connection closed by foreign host.

This kinda surprised me. Is this intentional? If inbound connections to port 25 are indeed supported, then I could reconfigure Postfix to push through a smarthost.
by ajay » Tue May 11, 2021 2:32 pm
Hey all,

tl;dr: I'm using a backup MX solution from and I'm curious to know what systems others have deployed as a workaround! Especiallly a solution that can use a secure port.

I'm having the same issue, and LMI just pointed me to sonic as the culprit. Bummer, I didn't know upgrading from Fusion to gigabit would cause me woes!
So I've spent a few hours looking at alternatives. LMI thinks I can use an alternate port, however as y'all pointed out, this is not how the internet works lol. So!
I've found this list, and am using the first free solution, forward email.
I've just been testing it out for ~20m and it doesn't seem to play well with my current setup (e4ward to gmail to my domain), so I may try changing things around and see if that helps.
I just looked through the rest of their FAQ, they've got a nice set of features! Ironically, the only way to turn off the spam protection that's causing me problems is to pay. (Ironic because i'd pay them to use their CPUs less:).

If it doesn't work out, I also found which is very cool, which will hopefully tide me over during any downtime. (They sport the EFF logo as a partner, which I'll take to be a good sign!)
I can't believe I didn't engage a backup MX server years ago. :)
I'd love to hear alternate solutions that people find to forward my mail to a custom port that are free! I do see several options for $10/yr.
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