Cloud-storage service Dropbox is investigating whether a security breach caused the barrage of spam emails sent to its users recently, according to a company blog post.

“While we haven’t had any reports of unauthorized activity on Dropbox accounts, we’ve taken a number of precautionary steps and continue to work around the clock to make sure your information is safe. We’ll continue to provide updates,” a Dropbox rep wrote in a post on the company’s discussion forum.

The trouble started Monday night when users, many of whom were based in Europe, began receiving strange emails, some related to gambling, CNN reported.

The San Francisco-based company said that it has brought in outside security experts to help with the investigation.

It also claimed that the service outage experienced by some users on Tuesday was not related to the spamming.

This is not the first time, however, that the popular cloud-storage service has had issues with security.

For a few hours in June 2011, users were able to log into Dropbox accounts without the correct passwords. Dropbox stressed in a statement via the company blog at the time that fewer than 100 users were affected by this security lapse.