The Web-based campaign was launched by the American Center for Law and Justice ahead of Abedini's 33rd birthday May 7.
ACLJ, which is representing Abedini's wife and children who live in the United States, reported that 52,501 letters had been written to the pastor, a U.S. citizen of Iranian descent who has been sentenced to eight years in prison for converting to Christianity. More letters can still be written at SaveSaeed.org.
ACLJ said it is printing out and delivering each letter through intermediaries to Evin Prison in Tehran.
The large number of letters also serves to let Iranian officials know that the international community is still fighting for his release, Tiffany Barrans, international legal director of the ACLJ, told the persecution monitor Morning Star News.
Abedini's wife Naghmeh, who grew up mostly in the United States and is a U.S. citizen, wrote a letter of encouragement to her husband that was published by ACLJ.
"With tightness in my throat, pain in my heart, and tears streaming down my face ... so very weak, I promise to stand strong in the strength of our Lord and Savior Jesus Christ fighting with every strength of my being until you are united to our family again," Naghmeh Abedini wrote.
"I will be a voice, where you are being silenced. I will be hands and feet where you are being bound and in chains. That the whole world would know, that the whole world would hear that Jesus is Lord," she wrote. "We are so proud of you. Hang in there. Hold on tight to Jesus. You have many brothers and sisters praying for you and standing with you."
Jordan Sekulow, ACLJ's executive director, said this is a crucial time for Abedini as his health continues to worsen at the hands of his Iranian captors who have beaten him continually, refused him medical treatment, pressured him to recant his faith and recently placed him in solitary confinement.
Sekulow reported that on the day before Abedini's birthday his father again was turned away by prison officials when he attempted a visit. Until recently, the pastor's Iranian family had been allowed to see him on occasion.
Abedini was sentenced in January for threatening "national security," which Morning Star News noted is a catch-all phrase often used by Iranian courts to imprison converts from Islam for various sorts of evangelistic activities.
Though he is receiving the most international attention, Abedini is just one of numerous Christians imprisoned for their faith in Iran. World Watch Monitor pointed to a report from Mohabat News, described as an Iranian Christian news agency, which said May 6 that an Assemblies of God pastor in Iran and three members of his church were summoned to serve one year in prison on charges of "converting to Christianity and propagating against the Islamic regime through evangelism."
In late 2011, Iranian security authorities had raided their church and arrested the four people as well as everyone who was in attendance at their church service, Mohabat News said.
"It is obvious that the restriction and arrest of Christian converts is not a new phenomenon in Iran," Mohabat News stated. "It is the strategy of the Islamic regime to prevent its citizens from exercising their rights and freedom."
Morning Star News reported a pattern of massive political arrests and executions that it cited as part of a general repression leading up to presidential elections in June.
Four Christian converts arrested last year each posted $80,000 in bail in March. A fifth is still in jail, Morning Star News said, adding that the judge intentionally set the bail amount high to financially cripple the Iranian Christian community.
Morning Star News said the men were not tortured in prison but their movements and privileges were limited. They reportedly were not allowed out for exercise, could not use the library and were limited in their contact with other prisoners.
The five men, who were arrested at a house prayer service, are members of the Church of Iran, a heavily persecuted denomination to which jailed pastor Benham Irani also belongs, Morning Star News said. Irani suffers from an acute blood infection and is barely able to walk as he serves a six-year sentence for "acting against the interests of national security."
Also imprisoned, facing a nine-year sentence, is Mohammad Ali Dadkhah, the attorney who defended another long-imprisoned Iranian pastor, Yousef Nadarkhani, whose freedom was the focus of a worldwide campaign that resulted in his release last year.
Khataza Gondwe, the Africa and Middle East director for Christian Solidarity Worldwide, said the practice in Iran of arresting and harassing Christians "is the procedure these days with cases of converts, and I think there is a message being sent out with them."