Walmart Inc. is investigating messages that included a racist slur sent from its email servers.

Twitter users have reported receiving emails containing a slur instead of their name from the email address “help@walmart.com.” The perpetrator or perpetrators created new accounts for people whose email addresses were not previously associated with a Walmart customer, but replaced the person’s name with the slur. That generated an automated account-creation email from Walmart.

Walmart’s internal systems weren’t compromised and no customer data is at risk.

The company is “shocked and appalled” by the messages and is “looking to hold those responsible accountable,” a Walmart spokeswoman said in response to an inquiry from Bloomberg News. The company blamed the situation on an “external bad actor.” Walmart is also looking into its sign-up process to receive automated emails.

So-called “spoofing” attacks can be damaging to a company as unsuspecting recipients often assume they are real. Sometimes these scams try to dupe the recipient into paying money, although that’s not the case with the Walmart emails. Recently, dozens of consumers were scammed by Elon Musk impersonators taking advantage of the recent cryptocurrency mania.