How often should an online service be able to contact people in your address book on your behalf?

For some (and perhaps most) LinkedIn users, once is probably enough. Maybe even that's too much. But now LinkedIn is paying $13 million to settle a class-action lawsuit that accused the company of acting too aggressively in trying to play professional matchmaker.

When you sign up for LinkedIn, the service prompts you to import your e-mail contacts so that it can send out invitations to connect with other people. Seems pretty standard, you might say. But what you might not know is that LinkedIn sends up to two more follow-up e-mails to your contacts reminding them of the original invite, if it isn't accepted within a certain time frame.

The suit raises bigger questions about e-mail etiquette at a time when many Americans are inundated daily with spam and commercial offers along with their more meaningful personal correspondence. The flow of messages not only makes it harder to separate wheat from chaff, but also poses security risks as hackers and criminals seek to trick users into clicking on bogus links or attachments made to look legitimate.

There's also the question of what online providers can legally do with the data you provide them. The class-action suit alleged that LinkedIn didn't get its users' permission before using their personal information. The court appears to agree at least in part: It ruled that users didn't consent to LinkedIn sending those reminder e-mails, even though they did agree to give LinkedIn access to their contact data.

LinkedIn isn't admitting to wrongdoing in the settlement. But in addition to paying $13 million, the company will offer a way for users to stop the follow-ups from being sent on their behalf. Its focus, the company said, will be on "finding additional ways to improve our member experiences."