3.A call for the expression of interest shall be sent to the Permanent Representations of the participating Member States, Missions of the third countries, the organisation or entity, as appropriate, and published on the Agency website. The call shall indicate the descriptions of the posts, the selection criteria and the deadline for the submission of applications. Candidates for an SNE post must be sponsored by their national authorities, organisation or entity. Confirmation is required in the form of a letter of sponsorship addressed to the Agency, as far as possible by the closing date for the receipt of applications and in any case not later than the recruitment date.