Yahoo! Mail Bug? Emails disappearing upon reaching 65,535 emails in one of the folders

I am very confused.

I subscribe to several email lists including MySQL and Ruby on Rails lists. Generally, I keep my mailbox clean except for a folder in which I was archiving messages Ruby on Rails.

A few days ago I noticed that my Ruby on Rails folder reached 65535 messages. Today, I was looking to reply to an email from Keith Murphy (to which I had previously replied as well) and was surprised to find that the particular message didn't show up in my search. This particular message was sent on April 30 so I started scanning all my emails received on that day.

Surprisingly, I didn't find it even after a careful visual scan. Not only that, I noticed several of emails I received in the last 2 weeks missing. My initial reply to Keith was still sitting in my Sent mail folder. My trash folder also had several emails that I had deleted but not the ones that were missing.

For the life of me I cannot figure out where these emails went. Then suddenly I noticed that the Ruby on Rails folder still has 65535. Which is very weird as this is an active list.

I decided to send an email with criteria that would make it land in Ruby on Rails folder. After 6 hours, the email is still isn't in my inbox.

With 65,535 being a magical number representing a limitation of 65,536 objects, I believe this is a limit of a Yahoo! folder. Not only that, it seems that once you hit that limit, all sort of weird things start happening. Like, in my case, random missing emails.

This is pretty upsetting as I am not sure how many of my emails are missing. As soon as I deleted a few emails to bring the count down to 65,535, new emails from Ruby on Rails list started arriving (although not the one I had sent myself earlier today).

Now, unfortunately, I feel paranoid, not knowing how many important emails I have lost.

So, I have decided to open a new email account fmashraqi at yahoo and will be updating my contacts to start sending me email on that address.

My reason for posting it on this blog is to ask the community members if they have noticed anything like this? I know 65,535 emails is an insane number of emails but at one point I was interested in archiving the list. With Yahoo! offering unlimited storage, I wonder why isn't this limit documented?