do not crash when we remove a contact for which neerby contcts are not in the same accounts. Fixes #8157

request archiving preferences only if server announce it supports it, and don't think it supports it while it's buggy. Fixes #7839

show error message when we try to connect anonymously to a server that doesn't support anonymous connection. Fixes #8138

correctly detect that key is not trusted before encrypting. Doc says: "gpg just prints a message to the console, but does not provide a specific error indication that the Python wrapper can use." Fixes #8040. See #8041