Be clear with them about what they can expect to receive when signing up (types of content, frequency)
Live up to your promises (if you say a newsletter will be monthly, send it monthly - not weekly or bi-monthly!)
Let subscribers easily change their preferences whenever they want to.
Those rates look about right to me Benjamin. We see the same with our customers (who are mainly B2C): A good open % for fairly broad segments is around 25%, but for very targeted campaigns we're seeing 50-60%.
For me though, clickthrough rate is a much better indicator of relevance. If subscribers are opening emails but not seeing anything of value in them, it won't be long before they stop opening...
How about setting the direction on the table to "RTL" (right-to-left) rather than the default LTR?
Sorry I haven't tried this myself; I tend to use the approach of having a separate table for each column, then I can stack and float them pretty flexibly.
Hey, at least you're doing some segmentation on your data :) Too many marketers don't.
If you're going to be living with your back-end CRM system for a while, it may be worth looking at an ETL (extract, transfer & load) system to build a 2-way sync interface. Some are quite pricey, but things like Mulesoft and Talend have an open-source version (or at least they did last time I looked).
Things will also be much easier if you only require nightly sync rather than near-real-time, because then you can consider file-based import/export rather than coding against an API.
... or see if you can get an undergraduate GWU computer science student interested in a project :)
I'd say the most likely source of changes will be the way that the ESP / editor is in-lining any CSS styles. There are several approaches to this, and if they're in-lining their "computed styles" (rather than just any explicit css declarations from your style block or linked css files) it will likely result in some differences.
In my experience responsive columns tend to be pretty stable across email clients; the biggest issue is the additional 1px border in Outlook. One thing you could try though is setting your tables to display fixed-width so that any internal stuffing from the ESP won't make them stretch horizontally - otherwise you may find the right-hand table dropping below the left (if you're using the multi-table approach).
I'd be happy to take a look at your HTML & CSS, and offer more detailed suggestions :)
Ah, sorry. For once I ignored the tech!!!
Our customers tend to manage subscriber preferences through our platform, rather than using an API sync - and I'm afraid I don't have very much experience with the MailChimp API
I guess the main benefit of letting the ESP take care of the "preference center" side of things, either as a separate page or as an embedded iFrame, is that you don't need to make any site or API code changes if you decide to add or remove opt-in choices.
Plus it's always a good idea to make the preferences page mobile-responsive, especially if you're sending responsive emails.
I work in this space, so keep an eye on things ;)
For a straightforward, easy to use email marketing tool I really like Campaign Monitor.
Pretty much all systems these days have an API for data sync, and some support automated CSV or Excel imports, so it really depends whether you need 1-way or 2-way data sync.
Oh, one more thought (sorry!)
Think about what you want to use as permission-based opt in choices, and what you want to collect as additional preference or interest data. The former is likely to be pretty broad, and the latter more detailed.
As you get more subscribers, this will let you do more in terms of tailoring the content in your emails. MailChimp and others let you segment your lists/groups, which can be very useful when you have news and offers that won't be relevant to everyone :)
I don't think the technology implementation matters too much here. The most important thing is to establish a good trust relationship with your subscribers:
We have some clients who offer preferences based on frequency, some on type of content (monthly newsletter, ad-hoc offers etc), some based on sub-brands, physical locations etc. What makes sense will vary from business to business - the important thing is to establish an honest, open, transparent relationship with subscribers.