How accurate are IP Trackers in terms of location?

[UnatcoAgent]

A friend at work got an email from someone and is trying to find out if the sender was in Canada at the time. We checked the IP against an ip tracker and it says that the email was sent in Britain.

Is it safe to assume this is accurate? Or can these IP trackers (we tried a few) screw up sometimes. We don't need his address or anything.

Thanks!

Rob