Comment 4 for bug 326841

Sebastien, yes it's reproducible (I tested this in two different fresh installations) even if sometimes, the problem seems to disappear. Anyway:

1) import a key with seahorse (the keys is put under collected keys)
2) sign the key and apply a trust level, for example, equals to "full"
3) try to send a new message, with evolution, to the owner of the previous key, and select "encrypt with pgp" in the security menu
4) when you click "send" you will have the issue (obviously I expect the email was sent as I signed the key so I have verified that the key belongs to the recipient user)

Possible ways to bypass this is:
1) via gpg cli, set the trust level of the key to "ultimately" (with seahorse you cannot as this trust level seems to be reserved automatically to own private key); obviously this isn't right as I shouldn't have to set this level of trust to send encrypted emails
2) checking the option "Always encrypt to myself when sending encrypted messages" but also this is not right as this option is not intended to choose if to send or not to send an email but to view pgp encrypted sent messages stored in "sent" folder