Help/Troubleshooting, 'Copy text to clipboard', paste into a reply here, omit everything after the 'Crash Reports for the Last 3 Days' section. Problems like this are often due to a mismatch between the sending account and the smtp server set for that account.

sfhowes -- many thanks for the rapid response. I've added the Troubleshooting information below.

I'm not ready to rule out -any- potential theories here, of course, but I'm not clear how the smtp server could have affected my first error example -- the inbound email came from gmail, through my pop server, and selecting Reply All shouldn't (I think) have considered outbound pathing for the new message that was being created. Messages to/from the other userids here tied to mindspring will naturally be using its pop and Earthlink smtp servers.

For a little more clarification: it appears that in the list below, "account 1" corresponds to the Local Folders Junk and Disk Space settings; "account 2" to MyID-1 from the original problem description; "account 3" to MyID-2; "account 3" to OtherID; and accounts 4/5 to leftover user/mail settings, which have not been active in years and whose servers no longer exist (time for cleanup, I suppose).

Troubleshooting info follows. If necessary I can create .pngs or similar files to provide more legible output.

 Application Basics

   Name: Thunderbird
   Version: 78.7.1
   Build ID: 20210203182138
   Distribution ID:

   Update Channel: release
   User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1
   OS: Windows_NT 10.0

   Launcher Process: Enabled
   Multiprocess Windows: 0/0
             Disabled
   Remote Processes: 0
   Enterprise Policies: Inactive
   Google Location Service Key: Missing
   Google Safebrowsing Key: Missing
   Mozilla Location Service Key: Missing
   Safe Mode: false

 Mail and News Accounts
   account1:
     INCOMING: account1, , (none) Local Folders, plain, passwordCleartext

   account2:
     INCOMING: account2, , (pop3) pop.mindspring.com:110, plain, passwordCleartext
     OUTGOING: , smtpauth.earthlink.net:587, plain, passwordCleartext, true

   account3:
     INCOMING: account3, , (pop3) pop.mindspring.com:110, plain, passwordCleartext
     OUTGOING: , smtpauth.earthlink.net:587, plain, passwordCleartext, true

   account4:
     INCOMING: account4, , (pop3) pop.mindspring.com:110, plain, passwordCleartext
     OUTGOING: , smtpauth.earthlink.net:587, plain, passwordCleartext, true

   account5:
     INCOMING: account5, , (pop3) mail.celebration.fl.us:110, plain, passwordCleartext
     OUTGOING: , smtpauth.earthlink.net:587, plain, passwordCleartext, true

   account6:
     INCOMING: account6, , (pop3) mail.celebration.fl.us:110, plain, passwordCleartext
     OUTGOING: , smtpauth.earthlink.net:587, plain, passwordCleartext, true

 Crash Reports for the Last 3 Days

 Remote Processes

   Type: Count

Accounts 2-5 send through the same server, but do you have 4 different smtp servers in Tools/Account Settings, Outgoing Server (SMTP), each with User Names corresponding to the 4 accounts? Plus, when you select an account in the left pane of Account Settings, does the smtp in the Outgoing Server (SMTP) menu in the right pane have the same User Name as the selected account? Click Edit SMTP server... to view the smtp User Name.

sfhowes -- hi once again.

In my original post I meant to include the outbound server setup: there is only a single Outbound/SMTP server definition, and so it is the default. The associated userid -- for id/password verification for server authorization -- is MyID-1@mindspring.com.

That is, all accounts use this single SMTP server and the one id for its use. The server doesn't care very much about any details beyond its need to verify that it is being targeted by an authorized -- mindspring.com, earthlink.net -- user.

As an experiment just now, I created different SMTP server entries for each account id. MyID-1 was then tied to SMTP server "MyID-1@mindspring.com -- smtpauth.earthlink.net", using access id MyID-1@mindspring.com, and similarly for the other two active accounts, each of which selected an SMTP server specific to the account's email address.

Repeating test #1 from way above, there are no differences in the symptoms:

From: someone@gmall.com To: MyID-2@mindspring.com To: MyID-1@mindspring.com

Reply All produces:

From: MyID-2@mindspring.com To: someone@gmail.com To: MyID-1@mindspring.com

The results of the other checks are unchanged.

One of these in particular suggests that the problem lies elsewhere. A copy of a note I sent last week resides in my All folder:

From: MyID-1@mindspring.com To: someoneleseentirely@substack.com

I wanted to Reply to this note to send it back to myself, with some added comments for future reference. Surely Reply ought to build a new note to MyID-1@mindspring.com? Well, no:

From: MyID-1@mindspring.com To: someoneelseentirely@substack.com

However, with Thunderbird v24.3, the same note, still in that level's All folder, displays this when Reply is selected:

From: MyID-1@mindspring.com To: MyID-1@mindspring.com

This is as expected; where 78.7.1's response seems just .. weird.

I'm not sure how to correct the problem, since the account/smtp assignments don't seem to be the cause. Are you using a profile in TB 78 that was previously opened with an older version? Rather than try to debug the current profile, it will probably be faster and more effective to create a new profile with 78, add the accounts, and test the configuration. Create and manage profiles from Help/Troubleshooting, about:profiles. The current profile would be unaffected, and if the new one works properly, data from the old profile can be transferred to the new one.

sfhowes -- your last proposal sounds very promising. I have reproduced the Reply/Reply-All problem on emails dated from many months ago, so the maltreatment here is either inherent in the 78.7.1 setup, or reflects some sort of strange difficulty in the profile data.

When I migrated Thunderbird's v24.3 data to Win10 and Thunderbird v78.7.1, I followed the published instructions -- made a copy of the c:\Users\xxxxx\AppData\Roaming\Thunderbird folder from the 24.3 machine; installed the newer Thunderbird, and exited out of setup and personalization; pasted in the Thunderbird folder in Roaming on Win10; and after a Thunderbird restart I (eventually) found the symptoms I am reporting.

I see now from Troubleshooting information that there is a second copy of the profile -- same name and extension -- located in c:\Users\xxxxx\AppData\Local\Thunderbird. This is the case for both program versions. I wasn't aware of this second profile, so didn't consider copying it as well to a new installation. Is this second copy necessary for Thunderbird transfer/migration to a different system?

Concerning the creation of a new profile: I will start working on that shortly.

I haven't yet found clear instructions concerning how to transfer all mail, address books, and so on from the old/current profile once a newer profile exists, though. Aside from the obvious -- I certainly want all of my mail to live in a single profile -- I won't be able to verify whether or not the Reply failures persist without access to the mail entries that demonstrate the problems.

Thanks in advance for this; and for all of your suggestions.

You can ignore the AppData\Local folders, as they mainly contain cached data. When copying between computers, the only important data are in the AppData\Roaming\Thunderbird folder.

See http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Thunderbird

which is mostly up to date, except TB 78 stores address books in sqlite format instead of mab.

sfhowes -- I apologize for my delay in responding. Work has intruded, and I have been experimenting further with old Thunderbird v24.3 and other mail clients for comparison tests.

Creating a new 78.7.1 profile and moving the important parts of mail over -- the mail file, address book -- proceeded smoothly and with no apparent problems.

My Reply issue continues for notes which "I" have sent (anything which is initially saved in the Sent folder).

After the last day+ of other testing, I now wonder whether there is in fact no official standard for the operation of the Reply function for those emails sent by the current user. My earlier statement that ".. of course Reply must create a response whose To: tag matches the From: value in the message being responded to .." now seems to be an opinion, rather than a fact.

I find with my mainframe Lotus Notes that Reply -- for a message my Notes id sent originally -- creates a new note whose To: entry is the first To: value from the original note (and so NOT a match for the original From: tag). This behavior is exactly what I see with Thunderbird v78.7.1.

The mail clients used by a few of my colleagues -- Windows, Linux -- generally but not always behave in this way as well for "owner-generated" mail. For such notes, a small subset of these clients generate Replies targeted to the original sender (their From: tags), but most seem to use the Lotus Notes/Thunderbird 78.7.1 "rule" as above.

PERHAPS my problem with Reply in Thunderbird is one of expectations rather than an actual code or setup error, in that I was convinced that v78.7.1 should act exactly as does v24.3. With the newer edition Reply to a note transmitted by the active user builds a response targeted to the original's To: field's value; while 24.3 Reply creates a To: tag that is the original note's From: entry.

While I'd love to know whether there is any record of a design change for Reply in Thunderbird's evolution between these two releases, I'll be satisfied instead with the result of someone else's quick experiment:

1. Create and send a note from Thunderbird to some other id on a different mail client. So, the From: value will reflect "yourTBid@yourmailserver.com" and To: will be "targetid@otherserver.net", or equivalent.

Something along the lines of -- in Thunderbird -- selecting Write, and choosing an outside address for the To: field, will do perfectly well. I'm certainly not asking anyone to flood Yahoo, say, with junk mall, but _as an example only_ a new Thunderbird note with "To: abcd1234@yahoo.com" would suffice.

2. This new/test note will appear in the Sent folder. Please select it, click on Reply, and then let me know whether the reply has From:/To: fields like this:

(a) From: (original sender, its From: entry)

    To:      (the first or only To: value in the original note)

-or-

(b) From: (original sender)

    To:      (original sender)

(a) is the approach used by Thunderbird 78.7.1, Notes, and many other email clients; (b) is (at least) the scheme implemented by Thunderbird 24.3.

If the answer from other 78.7.1 users is (a) -- then I will happily mark this thread as closed, write it off as the result of a long-ago design change, and express thanks once again to sjhowes for all the help.

Using 'Reply' on a message in your Sent folder is probably not the best approach. The standard method of re-sending a message you've already sent is to right-click, Edit As New Message. I think you'll find that avoids the addressing issues.

Concerning treating the reply function via Right-Click, Edit As New Message instead: entirely agree. (Or select Forward, or ..)

Overall the particular good news is that my Reply-to-Self "error" is merely the result of one or more (small) design updates as Thunderbird's editions were released over time. I have verified as well that a fresh installation of Thunderbird v78.7.1 on a "playgound" pc here, which was using an entirely different mail client, resulted in exactly the same Reply behavior I see with my Thunderbird upgrade on this particular machine. So: my reported issue was fundamentally a reaction to what can be characterized as "not a bug, but a feature."

sfhowes -- many thanks again for your time and assistance!