Dada Mail, version 2.11 is in heavy development - what is below is a, "sneak peek" to get you interested and drooling over the program. Things are rough, so be mindful that all this is a work-in-progress.
If you can, test out the latest development version of Dada Mail, report any questions, problems, bugs, ideas to any of these locations:
If any of the below features sounds enticing and you'd like development of them to move a little faster, the best thing to do is to commission some time towards the feature. Commissioning the feature will help ensure the feature works on your specific hosting setup and solves the problem you're having.
If this sound enticing, please do contact us directly with your idea. We'll chat about it and send you back a quote, once we've agreed on the plan of action.
Here's a major problem: Dada Mail is targeted to work from el-cheapo hosts, all the way up to your own dedicated server.
El-cheapo hosts have harsh restrictions on how much mail you can send at one time and how long a program can run - there's no getting around these limits - don't try.
These harsh limits don't work well with sending to your entire list. Usually, the mailing will fail mid-send somewhere and you'll have to manually pick it up. No fun.
So in version 2.11 of Dada Mail, we've basically solved the problem of dropped mailings - they'll be auto-picked up behind the scenes and you'll be able to monitor your mailing in a bit easier fashion than just the batch confirmation email messages/usage logs.
Currently, the monitor for all this looks like this:

Hopefully, this new revision (as of 2.11 alpha 3) is much more intuitive - The bar graph will give you a quick idea on where you are in your list, and the information below will tell you exactly how far you're gotten. The, "Verbose Sending Information..." link, when clicked, will tell you everything you posssibly wanted to know about the mailing. The new, "STOP Mailing" button will do just that.
The screen for the sending monitor will refresh automatically, check your mailing, and if it sees that it has dropped, will auto-pick it up. That's all there is to it. If you don't want to leave this screen open, which is understandable, you can set a small cron script to check for you. This should allow you to send to your list as slow as you need to and work with any draconian server resource restrictions you may have.
And of course, this is optional, so if this isn't something you want and mail sending was working just dandy before, you don't have to use it. This is what the settings look like to enable the feature:

So, if you ask me, "My mail sendings aren't finishing, what do I do?", I'll simply tell you to enabled the auto-pickup feature and we're done.
We've promised this forever and we're really really coming close to getting something tangible for you to play with, but it's been taking much more time than we've planned. We haven't been sitting on our haunches - the last release squashed 55+ bugs and this is a one man team. We (erm, I) decided to do the intelligent thing and fix problems, before building new features on an otherwise rocky foundation.
Saying all that, we did have a fundraiser and did garnish enough support to do the multiple subscriber fields feature - yeah!
We're still going to need people to help us test these features in real-world scenarios and here's the current scenario we want to target:
Do you have a CMS-based site, that already has a list of users, that you want to hook in Dada Mail seamlessly? If so, we want to work for you. If this is a problem you're trying to solve and want to use Dada Mail to do it (hey, why wouldn't you?) If you can donate some of the money to have the bridge between your CMS and Dada Mail work , we can help make it happen.
Again, please contact us directly if interested.
Email Sending/Receiving systems are based on open standards, but these standards also allow email servers to reject messages for odd reasons. Sometimes, it would be benificial to be able to tweak a mailing for one specific domain, and leave the rest alone. Well, now you can:

Basically, you have access to a small set of sending options that you can tweak per-domain. Handy.
We've hooked into SpamAssassin to make sure spam doesn't get through to your discussion lists. Here's what the admin screen for dada_bridge.pl now has:

It's really convenient, since you don't have to worry about blatant spam infiltrating your list. One less thing to worry about.
Moderation is now a part of the dada_bridge.pl plugin. Moderated messages will be routed to the list owner, who may allow or reject awaiting messages. Very simple, and really useful.
The bottom of archived message screens now have a row of social bookmarking/link sharing sites:

So your visitors can easily tag interesting archived messages and share them with friends.
Just another way to share/distribute the information you're sending out as a newsletter. All the bases covered.
CAPTCHA is a way to tell a flesh-and-blood human being from a computer robot and for Dada Mail, this can help keep your email list clean of spam bots trying to hack into your list. You've probably seen these types of tests before, where you have to enter in letters you see in an image. Here's what it looks like in Dada Mail:

This is (of course!) an optional feature, but if you want it/need it - it's there.
We really are looking forward to version 2.11 of Dada Mail.