Well, to be fair, I haven't quite given up on The Bat!, I've given up with its portable sibling, Voyager.
This is why.
I have a bad habit: I don't delete email that I might, conceivably, need again.
The Bat! allows this, on paper. I can create offline archives of mail, I can create rules and filters that let me handle automatically incoming email that I know I don't need to read but do need to keep, and I can do it in such a way that I don't have to store everything on mail servers that either have storage limits or might not be indefinitely reliable.
Add to this the fact that I've been moving more and more of my work into a portable environment, so I can carry a cheap portable HD with me rather than an expensive laptop.
The Bat! Home doesn't run portably. But upgrading to Pro allows the user to install Voyager, a portable version that encrypts the messagebases for security but otherwise works just like the normal version. So, some years back, that's what I did.
Every so often, I've fallen over bugs. Strange behaviours that I've reported to RitLabs, that they've investigated and, mostly, been unable to reproduce, and apparently unwilling to consider important.
For instance, creating virtual folders of unread mail items and moving emails from that environment to another folder in quantity often kills Voyager and corrupts messagebases.
Since the recent upgrade to version 5, for some reason my sent mail got picked up by a rule that had previously worked correctly and filed as incoming mail, and lost from the sent folders. So, a couple of weeks back, I decided I'd work through the rulesets and try to find out where the problem was but, before I did that, I'd search out my sent mail using Voyager's powerful search facilities and move everything it found to a single archive folder (in other words, in an account with no external links.)
Reloading Voyager showed that the several folders that had contained my sent mail were all empty. I ran maintenance. Maintenance claimed to have recovered several thousand messages and fixed the damage.
Guess what? It had done nothing of the sort.
Voyager also has the ability to run automatic backups. My most recent backup was only a couple of days old; I tried to restore the damaged folders from there.
That failed too.
RitLabs told me that my backups were not good enough, that if I want to be able to recover from these sorts of issue, I should keep better backups. Implication: their internal backup is not good enough.
There is no way, even knowing the encryption password, to recover mail using anything other than the installed copy of Voyager.
There are no guarantees that this won't happen again.
I've recovered what I can, exported it to mbox format and started using Thunderbird.
I've been recommending The Bat! for years, for anybody who wants something that can be made to jump through almost any hoops and who's prepared to get to grips with its complexities. I am no longer inclined to recommend it to anybody at all.
As there are a few Batfans around here, I thought I'd share...