I sent some emails from one of my email accounts and now it shows that these emails have been simultaneously sent from two of my email accounts

Question

I sent a few emails from one of my accounts that are set up in my Thunderbird. Now I see that they have been sent from two of my accounts, simultaneously. It shows them in both Sent folders and with the respective email address as sender.
Those email accounts have been set up in my Thunderbird for a long time now and have been working correctly until now.
How can I prevent this from happening again? I don't want to send people messages from two different emails at the same time.
I'd appreciate any help on this.
Thanks,
Borislav

Answer 1

In my case, TB is sending a copy of all my sent mail to the account that is associated with the smtp server. I have four accounts that I check via TB and the sent mail is being kept in the original folder and also in the sent folder of the account to which the smtp server is connected. If I change the smtp server from one gmail account to another, the sent mail follows. I then have two copies of the sent email, one in the original folder and one in the smtp server account's sent folder. I only want the one in the original folder. How do I stop the sent email from also being saved in the smtp account sent folder?