Even so, Raul Lopez-Vargas, a former vice president of the community group Centro Civico, walked alone into the consulate's busy lobby in Salt Lake City and hand-delivered the letter and several other documents.
Jose Umburto Gutierrez, the official who received the papers, said he would give them to his superiors. Lopez-Vargas said he already has sent a copy directly to Calderón.
The activist said he's doing this to pressure the LDS Church to sign the Utah Compact a document signed by more than 3,300 people who favor a compassionate approach toward illegal immigration. The church has endorsed, but not signed, the compact.
Lopez-Vargas also sent the letter in response to state Rep. Stephen Sandstrom's enforcement-only immigration bill, which cleared a committee Friday in a 9-3 vote.
That measure, asking local police to enforce immigration law, has been a hot-button issue. The Orem Republican changed the language last week to no longer require that local police question the legal status under "reasonable suspicion" of people pulled over for class B or C misdemeanors.
Sandstrom, who is Mormon, has called the move to put missionaries in the middle of the immigration debate "unfortunate" and criticized the activist for asking the Mexican government to interfere in internal matters related to Utah.
"They are trying to pass bills that violate human rights," Lopez-Vargas said after delivering his letter, signed by more than 130 people who are largely undocumented and living in Utah.
Asked for a response to the delivery of the letter, church spokesman Scott Trotter referred to the Utah Compact and reiterated the faith's support of its principles.
When asked whether the church had urged the Mexican government not to disrupt the visa process, Trotter said, "our missionary visas have never been part of this issue."
The global church is heavily invested in Mexico, with 23 missions, more than a million members and a dozen temples. Along with the United States and Brazil, Mexico brings in the faith's most new members every year.
In the late 1990s, the church encountered trouble getting enough visas for its U.S. missionaries so a leader met with Mexican officials there and succeeded in increasing the number from about 1,200 to more than 4,800, Pingree said. That made it possible for his mission to have an equal number of Mexican and U.S. missionaries, he explained, and they worked well together.
Pingree has maintained close ties with Latter-day Saints in Mexico and believes the percentages have remained fairly close to what they were in his time there.
"The church has been so positive on immigration," Pingree says. "Why would Mexico want to punish it?"
Peggy Fletcher Stack contributed to this story.