Solved

Our ISP Wants Us to Switch our SMTP Port - what options are there?

Posted on 2016-10-17
22
41 Views
Last Modified: 2016-10-25
Our ISP wants their customers to switch their SMTP port from 25 to 587.  They have only given us a three week notice.  Come the end of October, they say they will be blocking all port 25 traffic flowing through their servers, even if they do not host our email.

One idea we have, is to port forward SMTP traffic leaving our network from port 23 to port 587.  Is this possible?  Would a certificate be required?  We have an SSL certificate we have entered into Exchange, but I don't know if that is related.

We are told that many other servers are not setup to accept mail on port 587 (or something to that affect), and that our email would not be successfully accepted.  It sounds like we may need a third party service to switch our SMTP protocol back to port 25, and then forward it to servers that expect port 25 traffic.  

What options do we have?
0
Comment
Question by:tmaususer
  • 6
  • 6
  • 5
  • +1
22 Comments
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
You should not be using Port 25 because it will be used for spam. You should switch to Port 587 as they request. That is what I see in use everywhere.
0
 

Expert Comment

by:Mark Haggitt
Comment Utility
So,  can I use port forwarding.
0
 

Expert Comment

by:Mark Haggitt
Comment Utility
So once we switch our side to port 587, will other servers have any problems receiving our email?
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
Port 587 is for sending. Port 995 is for receiving. Once switched it should work.
0
 

Expert Comment

by:Mark Haggitt
Comment Utility
Just curious, is it the responsibility of the email host or the ISP to block ports?
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
They are controlling spam.
0
 

Expert Comment

by:Mark Haggitt
Comment Utility
I mean, in my Cisco firewall, can I use port translation to have all my out going email sent through port 587, or are there other considerations to be made in Exchange?
0
 

Expert Comment

by:Mark Haggitt
Comment Utility
Who is controlling spam?
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
Spammers use Port 25 to send out spam and get you Blacklisted.
0
 
LVL 82

Expert Comment

by:Dave Baldwin
Comment Utility
If your ISP starts blocking ALL traffic on port 25, that does mean that server to server traffic will be blocked and your email will not be sent to outside servers.  They block port 25 mostly for spam reasons but also because they don't want the extra server traffic on a residential account.  Most ISPs have a 'business' account available where port 25 traffic is allowed.
1
 

Author Comment

by:tmaususer
Comment Utility
Thanks Dave.  We do have a business account.
0
Enabling OSINT in Activity Based Intelligence

Activity based intelligence (ABI) requires access to all available sources of data. Recorded Future allows analysts to observe structured data on the open, deep, and dark web.

 
LVL 82

Expert Comment

by:Dave Baldwin
Comment Utility
Then you need to talk to them again and point out that you are hosting an email server which requires port 25 to talk to other email servers.  Which ISP is this?
1
 

Author Comment

by:tmaususer
Comment Utility
I'm talking to them now.  I have talked to them 3 other times.  On this call, It seems they my be confusing business and residential and that they were also assuming we used their domain name.
0
 
LVL 82

Expert Comment

by:Dave Baldwin
Comment Utility
Oh my...  The first people you talk to are 'phone answerers whose job is to prevent you from 'bothering' important people.  Only when you get past them do you have any chance of getting a reasonable solution.  I did say 'chance'.
1
 

Author Comment

by:tmaususer
Comment Utility
My ISP is Comporium.  I did get a reply last night.  They said that even thought I am a business and that they do not host my domain or email, that I will still need to change my ports.  Below is there reply.  So, what steps do I need to take, simply change the port number for outgoing email in Exchange?

"After speaking with SpiritDomains and our own Media Services department, I have found that we do not host the @tm-america.com

But, I spoke with our networking department and to my understanding they are blocking port 25 for all activity on our network. The reason for this is that we have had offenders spamming
through that port due to it being insecure and effectively having our entire subnet blacklisted by a lot of different domains. Which was causing particular businesses to not be able to communicate on our network.

Because of this you will have to switch all port forwarding (or any clients using port 25) to a secure connection on another port (such as 465)
If you have any questions please contact us at the number below."
0
 
LVL 82

Expert Comment

by:Dave Baldwin
Comment Utility
You can change the incoming port number for your clients but just changing the outgoing port number is not a solution as far as I know.  I think you still have to connect to port 25 at the remote email server.
1
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
We have a hardware firewall policy preventing anything / anyone but Exchange using port 25.
0
 

Author Comment

by:tmaususer
Comment Utility
Dave, thanks.
Yes, that is what we are hearing.  

We are told that our spam filter service can also provide something called Smart Hosting that will automatically forward our out outgoing emails from port 587 to the correct port on the receiving server.  Do you think this is an appropriate option?

I have been confused by the response below, which I know you didn't make.  

When I asked, "So once we switch our side to port 587, will other servers have any problems receiving our email?"

The reply was:
"Port 587 is for sending. Port 995 is for receiving. Once switched it should work."
0
 
LVL 82

Accepted Solution

by:
Dave Baldwin earned 500 total points
Comment Utility
Unfortunately, you are dealing with morons.  And I couldn't find another ISP for your area.  Port 587 is used for sending from a client to the server and 995 is used by the client to receive from the server.  I could be wrong but that's how my emails are set up.

If your spam filter service is located outside the Comporium network, you could call them to get their viewpoint on the problem.
1
 

Author Comment

by:tmaususer
Comment Utility
Good idea, thanks!  I did email the guy who was involved in setting up the network.  He said this isn't a simple matter.  I'm going to make a list of steps I think I need to take and post it.  Maybe you can help me see what I am overlooking or chasing my tail?
0
 

Author Comment

by:tmaususer
Comment Utility
I have made a list of steps I think I have to completed to successfully transition to port 587.
Could you let me know where I am barking up the wrong tree or completely overlooking something important?

1.       Run the shell command to switch outgoing mail to port 587.
2.      Change the port number in the SMTP Virtual Server.
3.      Change the port number in scripts or programs that specifically state port 25.
a.      Do I even need to worry about this internal to my network?
4.      Notify our third party spam filter to enable something like Smart Hosting so that our outgoing email can be switched back from port 587 to port 25 for receiving servers that require port 25.
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
I think the steps should work. As I noted, we block the use of port 25 at our hardware firewall except for legitimate (known) use.
0

Featured Post

Free book by J.Peter Bruzzese, Microsoft MVP

Are you using Office 365? Trying to set up email signatures but you’re struggling with transport rules and connectors? Let renowned Microsoft MVP J.Peter Bruzzese show you how in this exclusive e-book on Office 365 email signatures. Better yet, it’s free!

Join & Write a Comment

Find out how to use Active Directory data for email signature management in Microsoft Exchange and Office 365.
This process describes the steps required to Import and Export data from and to .pst files using Exchange 2010. We can use these steps to export data from a user to a .pst file, import data back to the same or a different user, or even import data t…
In this video we show how to create a Contact in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Recipients >> Contact ta…
The video tutorial explains the basics of the Exchange server Database Availability groups. The components of this video include: 1. Automatic Failover 2. Failover Clustering 3. Active Manager

744 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

17 Experts available now in Live!

Get 1:1 Help Now