Use default identity when replying

I receive mail via:

• foo@example-1.com
• foo@example-2.com, which forwards to foo@example-1.com.

In k-9 settings, I have an identity configured to send mail as: foo+mobile@example-1.com

When replying-all, because the inbound addresses are different from my outbound identity, the inbound addresses are not filtered from the To: or Cc: fields. Either:

• they must be manually deleted every time, or
• I receive a duplicate of my outbound reply, or
• I must add a new identity for foo@example-1.com, which is selected instead of foo+mobile@example-1.com when composing the reply.

It would be useful if I could either:

1. specify a default identity which applies even when replying, or
2. specify a list of additional addresses to strip from the To: and Cc: fields when replying.

P.S. thanks for the great software!

No file, test, or entry point is named. Start by locating the reply-all address filtering and identity-selection behavior, then determine whether the project supports a default replying identity or configurable additional addresses; done requires an agreed solution and coverage for forwarded and plus-addressed identities.