Yahoo Mail has been experiencing a major bug, following its revamp earlier this week. According to a number of reports, the service has been automatically forwarding emails to users’ “alternate,” external email addresses – a setting that was switched on without users’ permission. Yahoo has replied to some help requests via its Twitter account @YahooCare, but it hasn’t replied to help requests on its UserVoice forum, nor has its Customer Care site offered a solution to this problem. We’ve also reached out to the company for information on this and will update if/when we hear back. Some of the affected users have contacted TechCrunch tips and staff about the problem. It seems the bug has been in the wild for some time. Yahoo’s Mail upgrade took place on Tuesday, Oct. 8, when it introduced 1 TB of storage, “Mail Plus” features, and more. Complaints began showing up shortly after.