Outgoing Australia Post boss Ahmed Fahour has defended his controversial $5.6 million salary and said some criticism of him was linked to his Islamic faith.

On his last day at the helm of the government-owned business, Mr Fahour said critics of his $4.4 million pay packet and $1.2 million bonus overlooked the transformation Australia Post had undergone during his tenure.

He called for the organisation to stick to its public service roots once he left the job.

Mr Fahour announced his resignation in February, after a Senate committee refused to keep secret his salary.