While I have no idea what university, I must ask is the option actually effective on the exchange server. It has been the case that administrators of that package could over ride individual users choices and send return receipts regardless as "corporate" policy. So I suggest you ask the university IT department if they are imposing their choices on you.

Hi Matt!

Thank you for your reply!

I have sent an email to the university's service desk and I will come back to you when I receive a response. As far as I remember, however, I have been facing the same problem with another Outlook/Microsoft account in the past with Thunderbird. I cannot recall how and if I solved it, or if I just accepted and went with it. I think that Thunderbird faces this issue with all Outlook/Microsoft accounts.

How do you know you are reponding to a request for a return receipt ? Can you help me understand your situation by clarifying a couple of points?

For example: If I send email with request from account A to recipient account B and then choose to send the return receipt from Account B to A, there is no record in account B, but Account A receives email saying 'This is a Return Receipt for the mail...' If your mail account is 'B' the recipient: How do you know you are reponding to a request for a return receipt ?

If your mail account is the 'Sender'; so you would be the person requesting the return receipt, then you may get an email reponse saying someone has acknowledge your request. Are you getting this response? Is someone sending you the email 'This is a Return Receipt for the mail...' ?

Do you auto request for return receipt when you send emails?

Do you by any chance allow remote content for emails you receive in general or allow remote content for emails from university?

Hi Toad-Hall!

Thank you for your response!

Sure, let me clarify.

I had a Gmail account in Thunderbird and I also added the one from the university. So, I exchanged some test emails between the two, to see if everything works fine.

Therefore, when I am sending an email from the Gmail account to the university's account and open that email, a "Read: message" response is instantly sent back to Gmail. However, the option to send a Return Receipt is still there. If I choose to send it, a second "Return Receipt (displayed) -message" is also sent back. Please see the attachment to help you understand better. Perhaps the first one is not a Return Receipt then? If not, what is it and how could it prevented?

I am not allowing any remote content in Thunderbird, I write in plain text and I view in plain text.

In case you have any further questions, please feel free to ask me.

If you are using IMAP or POP, then Thunderbird will be operating exactly as it does with any other mail server. There is a chance there could be a variation of you are using an add-on to access the outlook server (exequilla) or an IMAP emulator that reads the outlook web app screen like davmail.

As you do not mention such extremes to access you mail I have assumed you are not using them.

What university is it? Might not help much, but it might help me build my knowledge of dodgy setups so I do not always have to guess.

Hi Matt.

Correct, I am not using any such add-ons.

The account is IMAP. It is from Aalto University of Finland.

I found something which sounds like what you are experiencing, but obviously cannot be certain.

• https://practical365.com/exchange-server/tracking-read-email-messages-exchange-server/

re : quote text: we can check the read status for a single recipient, by appending the -RecipientFilterPath and -ReportTemplate parameters.

When you select email to read, do you use auto mark as read option? Most people use this.

Perform a couple of tests: 1. switch auto mark as read option off in Options. 'Menu icon ' > 'Options' > 'Options' > 'Display' > 'Advanced' tab

Restart Thunderbird. Send an email from the Gmail account to the university's account and open that email. Is a "Read: message" response instantly sent back to Gmail?

2: 1. switch auto mark as read option back on in Options. 'Menu icon ' > 'Options' > 'Options' > 'Display' > 'Advanced' tab

Restart Thunderbird. Send an email from the Gmail account to the university's account.

This time move the email into 'Local Folders' and then open that email. So email is not actually opened in the univerity imap folder. Is a "Read: message" response instantly sent back to Gmail?

Please report back on results of tests.

Hi Toad-Hall!

First of all, thank you for your persistence and effort!

The solution is for sure somewhere around what you are getting at, however, switching the "Mark as read" option off still does not solve completely the problem. The results of the tests were the following:

Switched the option off, restarted TB, sent an email from Gmail to university's mail, opened the mail, NO "Read: Message" was sent back. There was were I thought "Here we are!". BUT! When I deleted the message from the university's Inbox, then a "Read: Message" was sent back. I verified that the "Read: Message" is being sent back when you move the mail out of the Inbox because I have re-sent another email from Gmail, left it on the university's Inbox without opening it, restarted TB a couple of times (no "Read: Message" was sent back until that point), but again when I deleted the mail, a "Read: Message" was sent back.

Same thing happens with the option either on or off, if you move the message to Local Folders before you open it. By the time you move it to Local Folders, a "Read: Message" is being sent back.

Hence, as far as I understand, a "Read: Message" is being sent back whenever there is ANY kind of activity on the received email.

So it would appear that the only way to stop a 'read message' would be to never use 'mark as read', and never move or delete !

The only other thing I can think of would be if you had a 'Message Filter' on the university account which would automatically copy incoming university emails to 'Local Folders'. Then view the emails in 'Local Folders' and never touch the ones in the imap Inbox. But it is unknown if the 'copy' would trigger that 'read message'; you could only give it a try?

Disabled the feature, sent an email to the university's account, copied it to Local Folders, opened it from there, no "Read: Message" was sent back... :P

One solution would be as you suggest, the other I can think of then would be to add a custom variable/rule in about:config. But what would that be..???

This is weird and slightly annoying... It is indeed an privacy breach...