[quote user="GordonM"]

Thank you for the clarification. The fact that John from the UK was able to connect to Rogers' SMTP service presumably means that his ISP is not blocking port 25 connections from "foreign" sources. This is, perhaps, surprising these days.

Gordon 

[/quote]

Indeed - I'm with Zen Internet, and they do not block or otherwise interfere with anything. I have a /29 IP block which is fully configurable from my ISP dashboard, so I can create DNS records for my IP range without having to bother anyone at Zen.

John.

I normally use the SMTP service provided by my ISP to send e-mails but, recently, there has been a problem, as a result of connections from my ISPs SMTP server being blocked when trying to send to Yahoo or Rogers (Canada) addresses.  My ISP is aware of this and is trying to find a solution but this has so far been unsuccessful.  It, therefore occurred to me that, perhaps, I could use Mercury E, the end-to-end SMTP client.  I have tried this, but the test was unsuccessful.  The Mercury E window on the dashboard showed the following:

Connection error during handshake with 74.6.137.45

13.06.53 processing job MO000004

Resolved MX for "Rogers.com; to 74.6.137.45

Connecting to 74.6.137.45

Connection error

The Mercury E log shows much the same information. 

Any help would be appreciated.

Hi Gordon,

The first thing I would do is to go back to basics and check you can connect to this email server. Try opening a telnet session on port 25 from your email server machine. I just tried this from the UK and everything seems to be OK for me.

Telnet

Open 74.6.137.45 25

220 mta4014.rog.mail.bf1.yahoo.com ESMTP ready

If you don't get the 220 response then your ISP is probably blocking port 25 and you're going to struggle to use MercuryE.

John.

Thank you John. Doing what you did produces an error 10060. I have also tried this with my ISP's SMTP server (that does block port 25 for customers).  The same error 10060 occurred.  However, if I do the same to myself I do get the proper response.

Maybe there is something in my router setup that is preventing these connections but that doesn't explain the non-connection to my ISP's SMTP server, which will send e-mail for me.

I have just tried something else, i.e. telnet smtp.teksavvy.com 25, and that works (Teksavvy is my ISP) 

Gordon 

Hi Gordon,

10060 is a socket timeout error, so it looks like you're getting no response back from the remote server. So the next question is do you have any antivirus software running that may be blocking port 25? Or perhaps the router's firewall is preventing port 25 access to the wider internet.

John.

Teksavvy blocks port 25.  That would explain you being able to connect to their server using port 25 and also being able to connect to your own server as it doesn't go through theirs to get to it.  If you have a static IP they may unblock it for you.  When people say port 25 is blocked they mean it is blocked to all IPs except their own.

From their support page (the last sentence mentions if you call them they will unblock it)
https://www.teksavvy.com/en/why-teksavvy/policies/legal-stuff/internet-traffic-management-practices

First, on all TekSavvy networks, we block traffic associated with three

ports, 25 (outbound), 53 (inbound), and 1900 (inbound), which are

typically associated with network attacks. Outbound port 25 traffic,

associated with TCP SMTP communications, is vulnerable to concurrent

connection attacks and spam abuse, so only connections to TekSavvy’s

SMTP server are permitted. Inbound port 53 traffic, associated with UDP

DNS server communications, is vulnerable to DNS denial-of-service and

related attacks. Inbound port 1900 traffic, associated with Microsoft’s

Simple Service Discovery Protocol, is similarly vulnerable to a range of

distributed DOS-style attacks. If you have a specific requirement

requiring that these ports be maintained open, please contact us. 

Thank you for the clarification. The fact that John from the UK was able to connect to Rogers' SMTP service presumably means that his ISP is not blocking port 25 connections from "foreign" sources. This is, perhaps, surprising these days.

Gordon