The new machines will be installed at the Leicester-based company by the end of September, after a three-month moratorium on reversion charges relating to sealing issues has expired.

Since the start of the year, the direct mail sector has been hit with millions in reversion charges on mailings after Royal Mail stepped up efforts to police its specifications.

The outcry this provoked caused the postal operator to refund the majority of charges and to put an embargo on future charges until September.

GI Direct client services director Patrick Headley said: "We are going to install a series of machines to counter the reversions issue.

"We stand a much better chance of having no reversion surcharges with this gluing kit. We have spent a lot of time trialling the technology and we will be doing more trials today.

"We are also working with Royal Mail to try to develop new specifications for peelable glue that works effectively for our customers and for Royal Mail’s machines."

GI Direct would not give specific details about the machines it has installed for competitive reasons.

Earlier this month Royal Mail presented a series of proposals on reversion charges to the direct mail sector, outlining how it plans to move forward after the three-month grace period has expired.