I also suspect that the copy is now preserved in the Sent Mail folder of "newguy @gmail.com" only because Gmail automatically saves any sent mail copy to that folder, so Tbird has no involvement in it. But some other email services may not have that function of auto copying to Sent Mail any message passing through their SMTP server. So in that case no copy will be preserved at all. There must be such option explicitely added to Tbird GUI.

I am just wondering why you would not just add the new email address to Thunderbird instead of messing with identities. But I largely fail to understand having multiple email accounts and a desktop email aggregator (thunderbird) and trying to use a web site to aggregate mail from multiple accounts.

Hi Matt, its a fair question. Many folks have multiple email accs, each used for a dedicated purpose. However, its not always convenient to add them all to Tbird on the desktop and also to various mobile devices, which creates clutter hard to deal with especially on mobile. That's why its often reasonable to Forward some email accs to other "task driven" aggregator emails on Gmail, and then add several such aggregator accs to Tbird and mobile email clients. This also allows to use much fewer acc passwords, which is important for mobile, especially when systems are frequently updated.

Anyway, since Identity feature is offered in Tbird, and based even on this forum its used by many, there is a compelling reason to make it complete by offering to explicitely choose the identity email address for preserving outgoing messages. Especially since it already used defacto by some SMTP servers like Gmail, but not used by other webmail services. It will allow to offer a uniform approach to users regardless of a webmail service choosen for the identity emails. Also, since such an important detail is not mentioned in Tbird Help or anywhere in support forums, it makes a lot harder to figure it out.

On a relevant note, if a user earlier added a separate email acc and SMTP server for it in Tbird, and later decided to add such acc and SMTP server as an "identity" to another primary Tbird acc instead, he must delete in Settings-Privacy-Passwords-Saved Passwords the previously saved by Tbird server password for that acc, so the Tbird could ask for a new password (it can be the same) at sending 1st email through the identity acc. Its not mentioned in the Using Identities or similar Help article either. Not sure why Tbird doesn't auto delete server passwords for deleted email accs or SMTP servers?

Would anyone suggest, where I can place a suggestion to Tbird developers or file a "bug" report if appropriate regarding adding an option to preserve outgoing email copies to an identity acc Sent Mail folder?

Would anyone suggest, where I can place a suggestion to Tbird developers or file a "bug" report if appropriate regarding adding an option to preserve outgoing email copies to an identity acc Sent Mail folder?

https://bugzilla.mozilla.org/home