Line managers are generally good.
We have weekly catch ups with our managers to provide feedback.
With an organisation as large as Australia Post, it is very easy to reach out to a manager and form a mentoring relationship with them. The graduate program co-ordinators also do great work in facilitating this.
They are easily accessible and are very supportive and good mentors.
Both my managers have made great mentors. Both allow me to have autonomy and trust me to complete the work.
Obviously depends on the person but there are plenty of people who are willing to help you out. For starters, you�re paired with a manager who has shown interest and a commitment to your development from the beginning.