Hi Jeff,
I must apologize for the delay in my reply! I went on vacation after my last post, and spent some additional time with family out of state. I am just getting back into the swing of things - my apologies!
I'm sorry to say that I currently don't have either Dada Mail or Pommo installed - I have typically used these for client installations that have been well received. However, I must admit that I like both applications for different reasons. I may end up installing the newest version of Dada 3.0RC1 to see some of the new changes.
You mentioned Mojo Mail which did became basis for Dada Mail. Dada is definitely a full featured application and further along in development than Pommo. Dada is Perl based (which may turn off PHP fans) however, it has proven to be a very reliable application. It can be configured with MySQL, PostgreSQL and SQLite. It is a bit more complicated at first to setup (installation, configuration and list building). The overall process for setting up lists reminds me of Major Domo as far as the overall functionality. Being Perl based, and due to my inexperience with Perl, it is also more involved to configure the appearance (it's easy to tell if a site is running Dada from the way it looks) - however, I believe the newest version offers templating for the actual interface. There are a wide range of config options that can be set including throttling, caching for delivery etc. Dada has a fair number of plugins including a log viewer that allows you to review statistics including click-throughs, errors and bounces as well as other statistics regarding recipient domains and such. HTML email is XHMTL compliant with a range of default templates to choose from. You can also integrate FCKEditor for a WYSIWYG editor. I must admit that I have not reviewed much of the formatting of the actual emails (I should - but was more focuses/pleased with the sending results). Of the installations that I have done, most customers maintain lists of 1500+ or so subscribers - easily handled. You can import/export subscribers with csv files (and I believe can now add single subscribers from the backend with the newest version).
Pommo mail is also an excellent option. It is PHP based and easy to install and configure (PHP, MySQL). The big selling point for me was the overall process of integration with an existing website as well as the ease of use for the end user (big plus here). It has a fair number of options - but not the complexity of Dada mail. I have found that customers lacking the technical expertise definitely need a much simpler interface. One feature I like is that you can dynamically design the signup form to include the specific fields that you want users to fill out (as well as setting field ordering and whether it is *required). Then it is just a matter of copying and pasting the html form into your website. Dada Mail also has this feature (form/field creation), however, it is more complicated for the average user. The management tools are not as full-featured as with Dada mail - however, this can be advantageous for a "non-techy" user. The ajax back-end and "web 2.0" feel to the interface are more inviting than the "strictly business" interface of Dada Mail (Literally a few clicks to make things happen). FCKEditor is also the WYSIWYG editor - from my experience with Drupal I believe the code is closer to being "XHTML compliant" than with TinyMCE (...hope I don't start a flame war
. You can import/export subscribers with csv files.
If I were looking at overall functionality the following would be my main points:
Dada Mail - Can install as a main application to handle mailing lists for multiple customers. If I needed something that would handle a large load this would be my choice. I might think twice about installing for a typical "non-techy" user, but would be comfortable knowing that it will work. Good performance, reliable and many configuration options + plugins. Interface is not as polished - you can also disable viewing of some options if it appears to be too complicated for your users.
Pommo Mail - I like Pommo for the ease of installation, configuration and interface. This is a good option for the "typical user" and is very easy for the non-techy. I am not certain of the overall "max" performance as compared to Dada - but it has worked out well for several of our customers. I have heard that "theoretically" very large list sizes are possible, however, one might need to tune MySQL's packet size in order to prevent large queries from Pooping out. The point and click process without all the config options is well liked by those who we have installed it for - especially the graphical interface. However, one the other hand, once you setup Dada your good to go - so the config options are really only something to work-out in the beginning. Pommo is a good option for the single-client installations.
I hope this is helpful and I would definitely suggest trying both to see what fits. I think they will serve the same purpose well. One thing that I would like to see is some performance comparisons between the two. I'm sure Dada will surpass due to it's maturity, but I have heard good things about newer versions of Pommo.
Michael