Fax to SMTP Relay Issue

Please bare with me as I am no where near an expert in FreePBX and I am learning about it every day.

We have PRI lines that come Ethernet into two FreePBX servers (PBX1 and PBX4). I would compare these to voice gateways in the Cisco world. We also have a third FreePBX server that serves mainly as the configuration system for our FreePBX install (PBX). I would compare this to a Call Manager in the Cisco world.

Our Telco provides us a set of fax numbers over one of the PRIs. (i.e. 123-456-7890). When a fax is made to one of those numbers, the fax is actually created as an e-mail and sent to an Active Directory distribution list which has an e-mail address example of [email protected]. Notice how the e-mail address is the last three digits of the fax number.

We have implemented a new SMTP relay server in our environment and shut down the old one. Not thinking about this fax creation using SMTP to create those e-mails, we broke the Fax to E-mail. We had to turn the old SMTP server back on. We have searched everywhere in all three FreePBX servers (PBX1, PBX4, and PBX) and are unable to find the location where this configuration is to hand these off to Active Directory. We did a Wireshark capture on the the old SMTP server while sending a fax and we did see where the relay (Port 25) was coming from PBX1 (one of the PRI connected devices).

Any help that anyone could give me around this would be greatly appreciated. We want to change the FreePBX config to point to the new SMTP relay server.

Assuming this is a distro install, the default smtp handler is a pretty generic postfix install. Default setup will lookup the mx record for the target address.

If they purchased sysadmin pro, then they may have set a relay under Admin->SystemAdmin in the GUI. Otherwise, they may have defined the relay using the postfix config files under /etc/postfix.

If it isn’t a distro install, then the first step will be to determine what mailer is running.

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Thank you for the information. I think we have a distro install. We DO NOT though have anything in the postfix files that point us to an SMTP server though. I did a “core show channels verbose” while a fax call was coming in and it shows the following information about the call:

This gives me the impression that we have some application running to create the fax and send the e-mail. We cannot locate this application to look into it though. Have you ever seen this before?

I wouldn’t assume that from this extract. What I see is the FAX receiver taking in a call and creating the output FAX document on the hard drive, probably in a sub directory under the extension.

Right now, from what I’ve followed on, is that you’re trying to solve a problem for three unknowns.

  1. Make sure you can send an email from your PBX server. This usually requires logging into an SMTP server somewhere and sending the file. Get this working (without worrying about the PBX) first.

  2. Set up Asterisk so that it can send emails. Once you have that solved.

  3. Make sure the FAX receiver is set up to send emails to the appropriate locations.

I haven’t got a warm fuzzy on the first two working, so spending a lot of time on the third step isn’t going to bear a lot of fruit fast.

Honestly, I may not have been clear in my description. I am really just trying to find where the current SMTP configuration is located so I can point it to a new SMTP Relay server. Basically, what happens now is the following:

  • A fax gets sent to one of our fax numbers (i.e. 334-386-6902)
  • When FreePBX takes the fax, somehow it captures it as a PDF file and sends it to an e-mail group.
  • The e-mail group that it sends too is the last three digits of the phone number with our e-mail domain appended. (i.e. [email protected]).
  • This leads me to believe the program that is creating/sending this fax is somehow stripping the phone number, creating the e-mail Send To: and then sending the e-mail to our SMTP Relay Server.
  • We have spun up a new SMTP Relay server and when we shutdown the old one, Faxes stopped working so we think there is configuration somewhere pointing to the old server that needs to be changed.

The email is sent to the address configured in Users for that extension. The config is easiest to do if you have the SysAdmin Pro module.

There is a bug where iFreePBX sends emails with the wrong from: address. This, to my knowledge, has not been fixed. So you have to define an additional SMTP address for the mailbox used to relay the messages on most mail hosts.

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