Sending an email with GMail app on Android in the Airplane mode produces the following message:
キューに追加しました "(the app) added (the message) to the queue"
Switching to English interface yields:
Queued (short for "The message has been queued" - I believe this is how most English speakers would interpret "queued").
The question is why the Japanese version is not passive past? Is it possible that 追加する an intransitive verb, and from what I observed, most Japanese intransitive verbs are best translated as English passive voice.