At the same event in 2013, three people were killed and 260 injured when two bombs exploded near the finish line.
The sportswear giant admitted its choice of words had been "insensitive" and said it was "incredibly sorry" for sending the document.
At least two survivors from the attack four years ago are known to have participated in this year's race.
Adidas, the official sponsor of the Boston Marathon, sent out the marketing email which contained the subject line, "Congrats, you survived the Boston Marathon!"
