Post Office partners such as Vodafone and British Gas have paid to appear in Sorted!, which has been created by Conde Nast's customer publishing division.
The Post Office decided it was necessary in order to provide its 28m weekly customers with a clear guide to its expanding range of services, which now include credit cards, gift vouchers and mobile phone top-ups.
The 3m circulation makes it the largest in-store customer magazine in the UK, ahead of Tesco Magazine's ABC-audited 2.49m bi-monthly copies.
The impact of the issue will be measured via BMRB Research, customer enquiries, and the Association of Publishing Agencies' effectiveness research project, the Advantage Study.
If the pilot is a success, the Post Office plans to roll it out as a quarterly title going to the majority of its 14,500 branches.
The A5-sized 68-page pilot issue was self-funding, taking into account contributions from advertisers and from Post Office divisions.
Lisa Samuels, the publisher of the magazine for the Post Office, said: "It's great to respond to the needs of customers in this way. We're confident that Sorted! will be a huge success."
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