The spondophoroi were special messengers starting from Eleusis to announce the beginning of the sacred truce and invite the Greek cities to send the aparche and the sacred ambassadors (theoroi) to the Mysteries. The ceasefire began on the fifteenth day of Metageitnion and ended fifty-five days later, on the tenth day of Pyanepsion.

The hierophant chose the spondophoroi from among the gene of the Eumolpidae and the Kerykes. They departed in groups, and at intervals, depending on the distance they had to travel. The spondophoroi carried customised messages written by the hierophant. They were not stereotyped or simple invitations, but letters of high diplomacy and rhetoric designed to encourage recipients to come to the Mysteries. The hierophant had to know the public to which he addressed each letter, the local traditions and the relationship of each city or group of people with Eleusis, Athens, and the Mysteries. Mistakes, failures, and insults would have a devastating effect on the reputation of the sanctuary and the organisation of the Mysteries.

A similar level of attention had to be paid to the selection of the spondophoroi since they constituted the sanctuary’s “public face” to the Greek world. The presentation of the message and the behaviour of the messengers in the cities they visited had to be appropriate to avoid misunderstandings or (even worse) the refusal to send the aparche or the theoroi.

The success of the spondophoroi had tangible results for the sanctuary and the gene of the Eumolpidae and the Kerykes. The more mystai and theoroi arrived in Eleusis, the greater the sacrifices made and the priests' and city’s income. It is no coincidence, then, that the gene had an interest in choosing the right people for the spondophoroi since part of the proceeds from the sacrifices and rituals were distributed to their members. Moreover, the hierophants recognised the pivotal role of the messengers and therefore had the right to reward them with honours after the successful completion of their mission.

As the fame of the Mysteries spread to the ends of the Mediterranean world, so did the spondophoroi missions. There is evidence of an entire convoy being sent to Egypt during the reign of Ptolemy or a group of messengers bound for Laodicea in Syria during the years of Antiochus. The refusal to participate in the Mysteries was an insult to the institution and the goddesses who protected it; therefore, it was rare but not impossible. In 367/6 BCE, the spondophoroi announced the sacred truce to the members of the Aetolian Confederation, who accepted the declaration. The Trichonians, however, captured the spondophoroi (named Prophetes and Epigenes) and provoked the angry reaction of the Athenians.