How many letters to raise support should I send?

Jesus made it clear He will provide for those He sends out on mission when He sent out the 72 with nothing but the clothes on their backs, and told them to look for those who would take care of their needs (Luke 10:1-8). He Himself, and the twelve who were with Him, were supported by the women who traveled with them (Luke 8:1-3). He sent His disciples specifically to the man who was preparing the upper room for Him (Mark 14:13-16), and even after His death His body was laid to rest in a tomb provided by Joseph of Arimathea (Matthew 27:57-60).

We who serve in ministry are to be responsible to do our part, as the 72 were instructed to seek out men of peace who would supply their needs. But clearly, those who provided them food and shelter on their mission journey had hearts that had been prepared to be generous when asked.

Surely all who give themselves to the mission call of the Lord of the Harvest can stand on His promise to supply their needs, even as the Apostle Paul did:

"Not that I [the Apostle Paul] am looking for a gift, but I am looking for what may be credited to your account. I have received full payment and even more; I am amply supplied, now that I have received from Epaphroditus the gifts you sent. They are a fragrant offering, an acceptable sacrifice, pleasing to God." (Philippians 4:17-18)

The next verse, “And my God will meet all your needs according to his glorious riches in Christ Jesus” (Philippians 4:19) includes the promise for those who give. There is certainly the sense that all who go on staff with e3 or join our mission teams are giving to God’s kingdom work. When we answer His call, will He fail to meet all our needs?