Yahoo Groups were nonfunctional all last week, according to customers complaining on the company's support forum and Twitter.

Yahoo Groups, which is a hybrid between a classic discussion board (forum) and a mailing list, was recently acquired by Verizon.

The issues appear to have started last Sunday, November 17, when users began complaining that they could not access the site, and when the site was up, users could not start new discussions and post new messages.

In addition, when posting messages and starting new topics was possible, Groups would not send email notifications to the other group participants. Similarly, Yahoo Groups would not create web posts for replies people sent in via email.

Businesses, PTA groups affected

Even if many moved social and event planning activities on Facebook, Yahoo Groups is still quite popular, specifically because of its post-to-email and email-to-post system.

The Yahoo Groups issues lingered all last week and affected many users, based on the number of user complaints Yahoo received.

Companies that relied on Yahoo Groups to send out Black Friday promotions were forced to move operations elsewhere. Similarly, many parent-teacher associations used Yahoo Groups for official school communications.

"I run an active parent group and it stopped sending and receiving messages as of November 19th - this is an active community of 2k+ members and people are freaking out but no one can communicate," said one distressed Groups administrator.

Yahoo says it fixed issues last Thursday, but some issues lingered

The issues were resolved on November 25, according to Yahoo, but some users still reported problems with messages being posted or sent via email with a considerable delay. By that time, it was too late for some customers.

"We’ve been down since Nov 19th. I’m about done also," said one user that was actively looking for alternatives.