How to make Reply (all), to an email I sent, to be sent from same account as the original email?

Question

I have a number of Email accounts configured, all of them as pop mail. And, they are all configured to use the same Inbox and Send folders, Thrashbin etc. They are all correctly configured with the appropriate Sender and Reply to-address.
My problem, has started occuring, I think, after I exchanged my default and some of my email accounts.
Sometimes I need to reuse a message that I have sent, to fill in some details, or whatever.
Typically I open an Email from the Sent folder, remove my own email from the distribution list, add some more text
and resend the message to the original recipients.
What I want, is for the new message to be sent from the same sender address as the original email.
But, since I changed my default account, the new email created by opening an email from the Sent folder
and clicking Reply or Reply all, now gets a different Sender and Reply to - address.
And this means I have to remember to edit the Sender address.
I seem to get this problem regardless of whether I do Forward, Reply or Reply all, to create a new Email from the old one I sent.
This is really a nuisance since I keep forgetting to do this, and it takes extra time and effort for something that used to be quick and easy.
How can I make Thunderbird include the correct Sender address, (the one that I sent the original email from) when doing this, without my having to change it manually each time?
The address Thunderbird chooses is not even my Default email address, but the first account that appears after the Default account in the list of accounts, at least that is what it seems like. I have tried to find a way to reorder the accounts, but I have not been able to find that.
Is there a way to reorder the accounts?
Would it help if I recreated the accounts so the one I use as default becomes the oldest one? But that, would help only for the default account, and the other accounts would still have the same problem, I assume?
I could live with this, since the default account is the default account for a reason.
Would it help, if I separated the different accounts, into different folders?
Or is there a setting to configure how Thunderbird does this, or even have it ask every time I create a new email from the Sent folder?
Each one of the accounts, is configured with the appropriate smtp server settings, (probably irrelevant for this problem).

Answer 1

Good suggestion. It gets rid of the "mailto:", but I have to remove the space after dragging the clip into the user name box. Interestingly, I can open the clip with TextWrangler, remove the space, and save it as a clip. However, the clip, as a clip, still has the space! When I open it again in TextWrangler, the space is gone, but still appears when I drag the clip or open it in the Finder. So not quite a cigar. But definitely useful.
So the question remains, where is a clip's data stored? Is it editable? If so, how? If not, why not?