> Is there a way to do that?

Apparently not. You could file a bug (https://bugzilla.mozilla.org/enter_bug.cgi/) for that. If you do, please post the link to it here.

https://bugzilla.mozilla.org/show_bug.cgi?id=2015873

I do not understand your problem. It needs more detail. I successfully test plus addressing and it works as intended. Part of your issue may be that you have a filter that strips the message. My understanding is that this is a feature of gmail. If you set up plus addresses as aliases in gmail, you can send and receive it. So, a message from a person using 'emailaddress+joe@gmail.com, can be readily replied to as emailaddress+joe@gmail.com. What am I not understanding here? I do not see a bug here. the plus addressing was defined by an email provider and that email provider administers these aliases, just as other email providers administer their aliases.

My guess is that you do not have the alias defined in your account. To function properly, aliases need to be defined in 'managed identities.' Try that and see if that fixes the issue. This is not a bug, and I want to help you get through the issue. thank you

My guess is that you do not have the alias defined in your account.

Thank you. Plus addressing is not aliasing. Plus addressing is adding a plus, +, after your name or alias. David, do you use plus addressing?

My awareness is with Gmail, where the plus addresses are defined. The email provider needs to acknowledge the plus address. if plus addressing is not dependent on the email provider's awareness, I have not heard of it. Is there a provider that does this?

Plus addressing is just gmails way of creating aliases.

You need to define each plus address as an identity in Thunderbird, and then it will work in Thunderbird. You don't need to take my word for it - create an identity and test it. https://support.mozilla.org/en-US/kb/using-identities

Hi, Wayne, it's been a few years...

https://support.mozilla.org/en-US/kb/using-identities is too abstract. https://support.mozilla.org/en-US/kb/using-identities shows no headers. https://support.mozilla.org/en-US/kb/using-identities has no examples.

I tried identities when it was an add-on. TBird got totally screwed up. It was a nightmare.

Is it too much to ask that TBird default the reply's "From:" header to the received "To:" header when replying?

My awareness is with Gmail, where the plus addresses are defined. The email provider needs to acknowledge the plus address. if plus addressing is not dependent on the email provider's awareness, I have not heard of it. Is there a provider that does this?

Thsnks, David, I don't know what "the email provider's awareness" means.

My error... I had misunderstood your response to imply that plus addressing could be added on the fly.

On your comment to Wayne, just to add my comment, since the feature you are wanting already exists in identities, I would question adding new code for this. But that's just my two cents and I'll back out of this.

My error... I had misunderstood your response to imply that plus addressing could be added on the fly.

It can be added on the fly, though not in TBird.

On your comment to Wayne, just to add my comment, since the feature you are wanting already exists in identities, I would question adding new code for this. But that's just my two cents and I'll back out of this.

Thank you, David. Kindly show me how to add it in identities. How would 'mark+joe@...' be created? I need an example. How would it default 'To: mark+joe@...', which is received, as 'From: mark+joe@...' when I reply?

One more point. I know that in plus addressing the email server adds 'ReplyTo: mark+joe@...' as part of that function. Gmail has been doing that for over a decade. Mailfence is doing it, too. Other email hosts are doing it. I'm going to drop Gmail in favor of one of those hosts because Gmail is forcing me off their service because I don't have a cell phone or text messaging.