One social media-born movement, #NoTraineeLeftBehind, is advocating a comparatively ancient form of communication: putting pen to paper -- and it's all for the sake of Soldiers.

While letters may seem outdated, they are one of few means of contact Soldiers-in-training have with the outside world.

The #NoTraineeLeftBehind Facebook group aims to provide every Fort Jackson trainee with one letter of encouragement and moral support during each phase of training: Red, White, and Blue.

Renae Reis, a Flint, Michigan native and current Las Vegas resident, launched the group in August, inspired by her son's experience at Fort Jackson. Reis started the group after her son, Pfc.Tyler Reis, went through Basic Combat Training at Fort Jackson during the fall of 2017.

"I realized I wasn't quite ready for him to go," Reis said. She wrote to him every day, beginning two weeks before he even left for training.

She didn't stop there, branching out to write letters to his entire platoon.

In the roughly seven months since its kickoff, more than 600 volunteers have signed up, sending an estimated 80,000 total letters.

Volunteers come from across the country. Others live overseas, from Puerto Rico to Germany.

Many are Army moms, but some don't have any military affiliation.

Each writes up to 70 letters to trainees at once.

Schools from across the country have also gotten involved. More than 8,000 elementary-aged students sent letters to Soldiers for Valentine's Day.

As an administrator for the "Fort Jackson: Basic Training Army Moms" Facebook group, Reis said she heard "countless stories" about trainees who weren't getting letters during their 10 weeks on-post.

"I just had a crazy idea," Reis said. She brought up the #NoTraineeLeftBehind concept on the Army Moms page Aug. 15.

Within a few hours, Reis said the post had been commented on nearly 500 times.

"(Writing letters) helps our moms stay busy," Reis said. "It keeps their minds less stressed about their child."

Ann Marie Smith is one Army mom who participates in the campaign. She started writing letters to Soldiers-in-training while her son, Pvt. Keiran Smith, was in BCT at Fort Jackson in September. That was before she even knew about the #NoTraineeLeftBehind movement.

Keiran told her how lonely some of the Soldiers in his unit felt.

"The stories I heard of some of the young kids crying because they felt alone was heart-wrenching," Smith said. "I wrote to my trainee often, but after hearing the stories, I decided to start writing to the whole platoon."

When Smith arrived at their BCT graduation ceremony, she realized the impact she had made.

Smith said she was "overwhelmed by the love and gratitude" of Soldiers she had written to.

"One Soldier told me it was the first letter he had received," Smith said. "Another said reading the letters of encouragement I sent helped them push through, knowing someone cared about them somewhere."

Trainees have written thank you letters back to volunteers in droves.

"I honestly teared up after reading (your letter)," one wrote to Smith. "I was having a rough day … and was honestly ready to give up. I've been very homesick. I have a young son whose birthday is next month, (and) I've been missing him dearly."

The letter brightened her spirits, she said.

"The day I received your letter, I was really starting to doubt if I was made for the Army," another trainee wrote. "Your letter gave me the motivation to keep on pushing."

To become a #NoTraineeLeftBehind volunteer, visit the #NoTraineeLeftBehind Facebook page and click "join."

Volunteers write or type 60-70 letters at once. Optional sample templates are posted online.