This is the 3297th most frequent Russian word.
отправлен
"Sent."
In this sentence, "отправлен" is used as the masculine singular past passive participle to describe that the package has been sent.
Пакет был отправлен вчера.
The package was sent yesterday.
Here, "отправлена" is the feminine singular past passive participle, indicating that the work is a feminine noun.
Работа была отправлена на проверку.
The work has been sent for review.
In this context, "отправлено" is the neuter singular past passive participle, showing agreement with the neuter noun "сообщение".