Allen Bradley Sending email to Port 2525 - PLCS.net

plcnewbie26 · May 10th, 2022, 03:00 PM

hi, I have a PLC that has been running for a few years now, and recently the SMTP was moved to a different server and IP address.

we noticed that the emails are no longer being received but the PLC is still saying that it successfully sent the email.

after investigating, it was discovered that the port # it's using to send the email is port 25. but it was originally configured (or sending) to port 2525. I'm not sure where to change this setting.

anything will help!

Thank you,

lfe · May 10th, 2022, 03:19 PM

A very common problem today by which devices such as scanners, PLC, HMI, etc. fail sending email is that they use TLS 1.0 or 1.1 protocols that are considered insecure and are rejected by more and more servers.

If your PLC says that it was sent successfully, it is probably not a port problem since it seems that it was able to connect.

Nor does it mean that it is that SMTP server that rejects the email, it may be that it is rejected by another intermediate server before reaching the recipient.

The solution is to update the firmware of the device so that it uses TLS 1.2 or later

plcnewbie26 · May 10th, 2022, 03:40 PM

Quote:

Originally Posted by lfe

A very common problem today by which devices such as scanners, PLC, HMI, etc. fail sending email is that they use TLS 1.0 or 1.1 protocols that are considered insecure and are rejected by more and more servers.

If your PLC says that it was sent successfully, it is probably not a port problem since it seems that it was able to connect.

Nor does it mean that it is that SMTP server that rejects the email, it may be that it is rejected by another intermediate server before reaching the recipient.

The solution is to update the firmware of the device so that it uses TLS 1.2 or later

do you mean update the SMTP server to use TLS 1.2? or the PLC?

Ken Roach · May 10th, 2022, 03:48 PM

This is a great question.

What exact model of A-B controller is sending the e-mail ? Please provide as much detail as you can about the configuration and program.

lfe · May 10th, 2022, 03:50 PM

Quote:

Originally Posted by plcnewbie26

do you mean update the SMTP server to use TLS 1.2? or the PLC?

The PLC

plcnewbie26 · May 10th, 2022, 04:03 PM

Quote:

Originally Posted by lfe

The PLC

I see. im guessing the only way to do this is via firmware updates?

plcnewbie26 · May 10th, 2022, 04:19 PM

Quote:

Originally Posted by Ken Roach

This is a great question.

What exact model of A-B controller is sending the e-mail ? Please provide as much detail as you can about the configuration and program.

the controller is a CompacLogix L35E. firmware 20.

I did receive information that the smtp server is using TLS 1.2 now when it was 1.1 before

lfe · May 10th, 2022, 04:27 PM

Quote:

Originally Posted by plcnewbie26

the controller is a CompacLogix L35E. firmware 20.

I did receive information that the smtp server is using TLS 1.2 now when it was 1.1 before

What defines the version of TLS is the sender, in your case the PLC

That rather sounds like the SMTP server used to accept TLS 1.1 and now it only accepts 1.2

lfe · May 10th, 2022, 04:31 PM

Quote:

Originally Posted by plcnewbie26

I see. im guessing the only way to do this is via firmware updates?

Or in the PLC configuration, if it allows choosing the TLS version

Ken Roach · May 10th, 2022, 05:04 PM

Thanks !

The 1769-L35E had a pretty limited e-mail feature, and it's documented in the User Manual (publication 1769-UM011) and in the RA Knowledgebase.

To my knowledge, the "EmailConfigstring" string that is used in those examples should contain only the hostname of the email server, or its IP address. There is no way that I know about to designate a TCP port number other than 25.

For better or for worse, the e-mail feature in those controllers did not support authentication. You may need a specially-configured old-stuff-only e-mail server, proxy, or relay.

Ken Roach · May 13th, 2022, 07:43 PM

On second thought: there at least three e-mail sample code releases in that era, including one described in Knowledgebase document QA26900 that includes a port number on the end of the SMTP address string and allowed basic authentication (though not encryption).

If you can post some details about the code that's running in the 1769-L35E, it might help folks narrow down which example you're using.

May 10th, 2022, 03:00 PM	#1
plcnewbie26 Member Join Date: Jan 2019 Location: Office Posts: 7	Allen Bradley Sending email to Port 2525 hi, I have a PLC that has been running for a few years now, and recently the SMTP was moved to a different server and IP address. we noticed that the emails are no longer being received but the PLC is still saying that it successfully sent the email. after investigating, it was discovered that the port # it's using to send the email is port 25. but it was originally configured (or sending) to port 2525. I'm not sure where to change this setting. anything will help! Thank you,

May 10th, 2022, 03:19 PM	#2
lfe Member Join Date: Jun 2007 Location: Barcelona Posts: 692	A very common problem today by which devices such as scanners, PLC, HMI, etc. fail sending email is that they use TLS 1.0 or 1.1 protocols that are considered insecure and are rejected by more and more servers. If your PLC says that it was sent successfully, it is probably not a port problem since it seems that it was able to connect. Nor does it mean that it is that SMTP server that rejects the email, it may be that it is rejected by another intermediate server before reaching the recipient. The solution is to update the firmware of the device so that it uses TLS 1.2 or later __________________ Suppanel HMI

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May 10th, 2022, 03:48 PM	#4
Ken Roach Lifetime Supporting Member + Moderator Join Date: Apr 2002 Location: Seattle, WA Posts: 16,513	This is a great question. What exact model of A-B controller is sending the e-mail ? Please provide as much detail as you can about the configuration and program.

May 10th, 2022, 05:04 PM	#10
Ken Roach Lifetime Supporting Member + Moderator Join Date: Apr 2002 Location: Seattle, WA Posts: 16,513	Thanks ! The 1769-L35E had a pretty limited e-mail feature, and it's documented in the User Manual (publication 1769-UM011) and in the RA Knowledgebase. To my knowledge, the "EmailConfigstring" string that is used in those examples should contain only the hostname of the email server, or its IP address. There is no way that I know about to designate a TCP port number other than 25. For better or for worse, the e-mail feature in those controllers did not support authentication. You may need a specially-configured old-stuff-only e-mail server, proxy, or relay.

May 13th, 2022, 07:43 PM	#11
Ken Roach Lifetime Supporting Member + Moderator Join Date: Apr 2002 Location: Seattle, WA Posts: 16,513	On second thought: there at least three e-mail sample code releases in that era, including one described in Knowledgebase document QA26900 that includes a port number on the end of the SMTP address string and allowed basic authentication (though not encryption). If you can post some details about the code that's running in the 1769-L35E, it might help folks narrow down which example you're using.

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