I had previously enjoyed some success with the Remove Duplicate Messages (Alternate) (RDMA) add-on (version 0.3.9) in Thunderbird 15.0. I had a folder in the Local Folders section called Email Archive. I selected that folder and then chose the Tools > Remove Duplicates menu pick. I got this message:
Not searching special folders
I had successfully used this RDMA add-on in the past. I was not sure what had changed, or what this error meant. A search yielded no joy. There was a bug report dated September 23, 2013, within the list of bugs for this add-on, stating, “Searching subfolders no longer works since 0.3.8.” It appeared, in other words, that something like this bug had been reported more than a month earlier and yet had not been resolved. Discussion of the bug had been underway within the past few weeks, though, so it seemed that the programmer would want to hear about my problem. I filed a bug report (no. 25621) and looked for other solutions in the meantime.
I wondered if an update would solve the problem. I appeared to be using the latest version of RDMA (the version history had not been updated since 0.3.7, but I had Thunderbird set to Tools > Options > Advanced > Update tab > Automatically check for updates to Installed Add-ons). But my Thunderbird version 15.0 was apparently far outdated; they were up to version 24 now. I went into Help > About > Check for Updates > Apply Update > Restart Thunderbird. Unfortunately, the “Not searching special folders” error reappeared when I tried again to run RDMA in the Email Archive subfolder.
I looked for alternatives to RDMA. A search seemed to indicate that Remove Duplicate Messages (not “Alternate”) (RDM) was the chief if not only option. It seemed to me that I’d had a bad experience with RDM. The Mozilla Add-ons page for RDM contained a substantial number of one-star (i.e., very unhappy) reviews. A very recent example said this:
WARNING! This is not an add-on. This is a virus – a least it works so. It has successfully destroyed half of my messages. This should be BLOCKED!!!
I decided that use of RDM would best be preceded by a careful backup of my Thunderbird files. For now, since I wasn’t in a rush, I decided to wait and see if RDMA’s developer fixed the problem.