The Travelodge UK hotel chain has issued a warning to users of its online service to watch out for spam e-mails.
"A small number of you may have received a spam e--mail via the e-mail address you have registered with us," said the letter signed by chief executive Guy Parsons.
According to the letter, no financial information has been compromised, but Travelodge says it is conducting a comprehensive investigation.
The letter contains no information about how the e-mail addresses were obtained, but says Travelodge has not sold user data to a third party.
The letter advises customers to delete any messages that are similar to e-mails some customers have received that offer an "exciting career opening" and "brilliant income ability" at a company seeking "self-motivated people in United Kingdom" to help spread activity in the UK area.
Travelodge says a further update will be given once it has completed its investigation, but gives no indication of when that is likely to be.