The TNT shareholders have between Monday and 30 October to accept the proposed acquisition offer from FedEx.
A joint statement from the two companies said the deal will be discussed with shareholders at a meeting on 5 October.
The offer made to shareholders is a public cash offer, priced at €8 (£5.77) per ordinary share, providing at least 95% of shareholders vote in favour of the deal.
However that figure will be reduced to 80% if shareholders vote in favour of asset sale and liquidation, as it is thought this would increase deal certainty.
The joint statement said: “The Executive Board and the Supervisory Board of TNT Express fully support and unanimously recommend the offer to all shareholders for acceptance.”
According to the joint document PostNL, which currently holds around 14.7% of TNT’s shares, has “irrevocably undertaken to tender its shares under the offer”.
The offer places the value of 100% of TNT's shares at €4.4bn (£3.17bn).
The companies seem confident that the deal is set to progress, predicting it will be completed in the first half of 2016.
Earlier this month the EC launched an investigation into the proposed deal, having said it was concerned that the merging of the two companies would create a company with an unfair market share, limiting competition in the sector.
In today’s statement, FedEx and TNT said: “The process of obtaining all necessary approvals and competition clearances is on track and evolving in line with the previously communicated timetable.
“The transaction presents a highly pro-competitive proposition for the provision of small package delivery services within and outside Europe that will benefit consumers and SMEs in Europe and beyond.”