Paul is giving thanks for the financial assistance and at the same time he defends himself writing that he had not solicited funds from the Philippians (Phil 4:17), and that he needed nothing more (4:18). Why?
The fact that Paul received money on a fairly regular basis from Philippi implies some organization. The church there must have delegated responsibility for the collection and transmission of funds to certain members of the community. In all probability these individuals were the episkopoi kai diakonoi ‘supervisors and assistants’ who are mentioned in the address (Phil 1:1). With regard to its leadership structure Philippi was exactly the same as the other Pauline churches. Paul did not select leaders. He expected them to emerge from the community as their gifts were expressed in service. What he says to the Philippians, ‘Mark those who so live as you have an example in us’ (3:17), echoes what he had written to the Thessalonians (1 Thess 5:12).
The Philippians were actively participating in the evangelization (Phil 4:3). It was time and energy consuming. They still had to earn a living. Yet they were in much better position than a missionary like Paul. They had remunerative occupations with an established clients and a stable network of family and friends. A new city offered Paul no guarantee of employment. He was always the vulnerable outsider, operating without any network of connections. On the basis of their own experience, the Philippians recognized that if Paul was to live as an apostle he needed to be subsidized.
Paul was very eager to help the poor (Gal 2:10). But at the same time he realized that with this eagerness his life would become more difficult. As the demands of his ministry became more pressing, the less time he had to earn his living, and the more dependent he would become on gifts from others. Now that he was committed to requesting funds to be held in trust for Jerusalem, it became imperative for him to devise a way which would make clear that he was not using for his own needs money given for the poor of the Holy City. It has to be remembered, that Paul lived in a world in which every official stole from the public purse; questions were raised only when they took too much. To avoid being accused of such a thing Paul devised a neat strategy (1 Cor 16:1–4). He asked the people to save weekly for the poor in Jerusalem. He was not responsible for safeguarding funds entrusted to him. Once the contributions were assembled, they were the responsibility of representatives of the donors. Paul himself was involved with the transmission of the gifts to Jerusalem only to the extent that his accompanying letter identified the gifts as the fulfillment of his promise to James, Caphas and John (Gal 2:10). Despite such precautions, it seems that rumors were going on among the churches undermining Paul’s reputation in money matters. The constant support from Philippi could contribute to those rumors.