I am truly sick of posting this.

The risks associated with opening mail are grossly exaggerated and relate almost exclusively to Microsoft mail clients. Thunderbird only displays "sanitized" HTML. It does not display remote images. It allows no scripts particularly VBscript or JavaScript. IT does not open OCX programs in mail. So the only real risk associated in opening a mail is an attachment.

As an attachment is simply an encoded text document until you choose to actively open it, and it is converted from text to binary, it represents no more risk that your name written on a piece of paper until you open it. The very act of opening it creates a binary file in your temp folder. Your anti virus should be scanning all new files and flag it as a problem long before there is a chance to actually open the attachment.

Ipso facto you do not risk downloading and installing malware by opening an email, regardless of the urban myths created largely by Microsoft to justify the insecurity of their mail offerings.

Read/ unread is purely an indicator. It has no real significance. If you go to tools menu (alt+T) > options > Advanced > reading and display you can change when a mail is marked as read from immediately to 10 seconds (that is what outlook express used) up to 1000 seconds. The timer for "mark as read" only starts when the body of the mail is displayed, either in the reading pane, a tab or a new window.

Did I open the e-mail or not in the situation I described?

Read the answer! Your question is answered in there.

Read/ unread is purely an indicator. It has no real significance. If you go to tools menu (alt+T) > options > Advanced > reading and display you can change when a mail is marked as read from immediately to 10 seconds (that is what outlook express used) up to 1000 seconds.

Has the software marked the email read is as far as that logic can go. It is still bold, so the software has not marked the message read.

Did you open the mail? This is a non quantifiable statement.

In the context of Thunderbird an individual mail is not a discrete item that is stored. It is a part of your mail/News data. So trying to equate opened to the action just does not fit.

Thunderbird received the mail as a series of lines. It compiled them into an email that it stores in a file along with all your other emails for that folder. Did you open the file the mail is stored in? Totally irrelevant as Thunderbird opens it to get mail every time new mail is added to the folder or to display a mail in that folder.

Every time a mail is displayed (any mail) the file all your emails for that folder are stored in is opened and read.

So did clicking on the mail in the list "open" the file. Probably not, it was probably already open. The file has been opened, read, written to and updated probably half a dozen times since Thunderbird started so if you click on the mail to view it is not going to change anything much at all. If the mail file was closed it will be opened to display the mail content, but it may already be open.

The bottom line is you are trying to apply assumptions to mail that simply do not apply. Hence I sound like I am going in circles.

You might as well be asking, when to I fill the kerosene reservoir in my electric light.

• The software marks mail as read when you say so
• It opens the underlying storage files constantly. Clicking an entry may or may not cause the file to be opened.
• Your mail is not in a file on it's own, it is in a file that also contains all mail in the folder including deleted mail until the folder is compacted.