WASHINGTON—Google Inc. told lawmakers it continues to allow other companies to scan and share data from Gmail accounts, responding to questions raised on Capitol Hill about privacy and potential misuse of the information contained in users’ emails.

In a letter to senators, a top Google official said the company allows app developers to scan Gmail accounts, even though Google itself stopped the practice for the purpose of ad targeting last year. The company also disclosed that app developers generally are free to share the data with others, as long as Google determines that their privacy policies adequately disclose potential uses.