When sending a signed email, we always "encrypt to self" in addition to encrypting to the recipient. We currently don't support "encrypt to others, only", as it would be confusing if the sender isn't able to read their copy in the sent folder. That means, encrypting to self could also leak who the real sender is.
Bug 1884463 Comment 6 Edit History
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When sending an encrypted email, we always "encrypt to self" in addition to encrypting to the recipient. We currently don't support "encrypt to others, only", as it would be confusing if the sender isn't able to read their copy in the sent folder. That means, encrypting to self could also leak who the real sender is.