With the FiltaQuilla add-on, a filter action 'Save Message as File' is available:

https://support.mozilla.org/en-US/questions/1014161

Messages are saved as Mail Files (eml files) with the Subject as file name.

If you made a filter to copy or move messages to a folder, they could be manually exported to individual text files or a single text file, with custom file names, with ImportExportTools.

FiltaQuilla installs just fine. But it's functionality does not solve my problem because I need the files saved in .txt format, not in eml format. the .eml format will open in Notepad, but contains a lot of additional information besides the body text. It will do if nothing else is available. Now, the Import/Export Tools extension, instead of the Green "+ Add to Thunderbird" box has one that is Orange with stripes and when you click on it states " Install add-ons only from authors you trust." and when you view the information on the Add-On it has this warning about permissions once installed "Please note this add-on uses legacy technology, which gives it access to all browser functions and data without requesting your permission." So how do I know the add-on does not contain malicious code (no MD5 has or SHA-1 hash to check for modification was available) And that's a concern. So I won't be installing that add-on.

So the problem I am trying to solve is this: I get e-mails every 4 hours from six remote systems with collected temperature and humidity readings in a text format. I will be adding more in the future. I am trying to avoid opening my network firewalls up for a more direct transfer as I get hammered enough by nation-state threat actors trying to hack me as it is. Data transmission via e-mail seemed like a simple solution as the data is not required for rel-time use.

The data looks like this:

==================================

| Date | Time | Temp | Humidty |

==================================

[stx] 12/13/2018 00:08:08 69.96 F 38.41 % 12/13/2018 00:18:11 69.78 F 38.33 % 12/13/2018 00:28:14 69.64 F 38.18 % 12/13/2018 00:38:17 69.47 F 38.28 % 12/13/2018 00:48:20 69.33 F 38.21 % 12/13/2018 00:58:23 69.19 F 37.96 % ... [etx]

I want to be able to save those e-mails out to a flat text file for processing into an SQL database by another program that parses out the data between the [stx] and [etx} markers.

Today I have a message filter that moves the received e-mails into save mail folders by system based on the subject line which contains the system name. So I could spend my time to manually extract the 36 files each day using the "More Actions" button after opening each message. But that's not really practical. What I was looking for, since the functionality already exists in Thunderbird except for the link between the "Save as..." feature under "More Actions" and the "Message Filters" function was a way to automatically perform the .txt file format extraction to a directory I indicate on my local hard drive when the incoming message is filtered. Naming the extracted file using message subject line would work fine as long as it can extract the message body to a flat file on my local disk. FiltaQuilla will have to suffice at the moment. But that's what I was inquiring about. Maybe it is not as simple as it would seem. Thanks for your reply and your consideration of this suggestion.

I think your concerns about ImportExportTools are unwarranted, as this is a well-known add-on used by almost half a million. But that is your decision. Exporting a folder of messages to text files is a 2-click operation with IET. There is no other way to save messages as plain text files through a filter, so you may have to consider an external program to read the eml files and extract the text.

I appreciate you taking time to reply. I'll work with what I have and move on. Thanks for your time.

One more option: if you could get your monitoring system to send the data as text attachments instead of in the message body, then, with FiltaQuilla, you could make a filter that detaches or saves attachments.

First it was not my intention or desire to demean the IETools or its author, just a personal decision to not install in light of the warnings. My sincere apologies if anyone was offended.

Second, I have devised a reasonable workaround, which I am testing now, using FiltaQuilla to solve my immediate problem. Creating the attachment on the remote systems was already tried a while back with less than successful results and as these systems have been doing the e-mails for over three years with no problems, I opted not to go down that path again.

Thanks again for your time. I appreciate your comments.