The sportswear giant admitted its choice of words had been "insensitive" and said it was "incredibly sorry" for sending the document.
The company "deeply" apologized for what it said was a mistake.
Instead the company congratulated those who "survived" the Boston Marathon and apparently forgot about the 2013 tragedy at the race. She placed 24th for women in the 2017 Boston Marathon.
In a statement to TIME, a spokesman for Adidas apologized for the email.
The first woman to officially run the Boston Marathon has marked five decades since her achievement by running it again - at the age of 70.
In 2016, a movie titled Patriots Day, starring Mark Wahlberg and Kevin Bacon, was released.
"Adidas, you may want to rethink the subject line", wrote Mike Denison. Kendall Jenner's Pepsi scandal was the most popular among them.
Switzer won the New York Marathon in 1974 and continued to run Boston until 1976 before providing TV commentary for the next 37 years.
A poorly worded email has people on social media wondering when Adidas may issue an apology.
The Boston Marathon was the target of a terrorist attack back in 2013 that ultimately killed six people and injured hundreds of others.
"Adidas is going to have to fire whoever was in charge of writing this e-mail", one person wrote on Twitter. "We can make it happen through running".
Donald Trump Signs Bill to Extend Veterans Choice Program
Babri demolition: Uma refuses to resign, says conspiracy charges not proven
Jeter, Bush join forces in bid to buy Marlins
Bayern Munich want answers over fan treatment in Madrid
PM bars party workers from going to Supreme Court today
Facebook Is Working on Letting You Type With Your Brain
Markets Right Now: Banks lead early stock gains
Malcolm Butler signs restricted free agent tender with New England
Celtics' Thomas: Days since sister died hardest of my life
Billionaires, companies power Trump's record inaugural haul
Kendall Jenner reveals she has 'panic attacks' after being stalked
21st Century Fox investigating O'Reilly harassment claims
Snapchat denies its CEO labeled India as 'poor'
Australia scraps visa for skilled foreign workers
Posh day at palace: Victoria Beckham gets royal recognition
Google, an ad company, will soon block 'bad ads' in Chrome
Portland's Nurkic out Game 2, Warriors' Durant questionable