Mailchimp is full of features. One of the most commonly used feature is creating custom fields on your Mailchimp lists. For situations where you want to have a limited number of options, Mailchimp allows you to create dropdown or radio button fields. For more flexibility, you can use Mailchimp Groups.
Syncing with Mailchimp Dropdowns and Radio Buttons
If you are wanting to sync a SugarCRM Dropdown field with a Mailchimp Dropdown or Radio buttons, there is one thing you need to make sure is setup to ensure it works properly. Go to your Dropdown list in SugarCRM and make sure that the labels match EXACTLY as you see them when looking at the Mailchimp Dropdown and Radio Button definitions. If those lists do not match up, there's a good chance the sync will not work as expected. If you ever change your dropdown list in Mailchimp or SugarCRM, you need to make sure you go to the other side of the integration and make the same updates.
If you haven't heard of Mailchimp Groups, they are a great feature for dropdown/radio button-like functionality in Mailchimp. They have more flexibility when segmenting in Mailchimp because they allow for multiple selections. The following video explains more about Groups.
Syncing with Mailchimp Groups
Mailchimp Groups are a great tool for further segmenting your list data in Mailchimp. They are the only way to sync multiselect fields from Sugar to Mailchimp. You can only sync Mailchimp Groups with dropdowns or multiselects from Sugar. SugarChimp will keep this data in sync for you automatically. To set up a group, follow the directions here. Note that you will only need to add one option in the group, as the next time Sugar syncs to Mailchimp, the other options will populate from Sugar automatically.
For example, say you have a Mailchimp Group that is called "Email Newsletter Preferences" and the subgroups "Monthly Newsletter", "Press Releases", and "Product Updates" and you sync it with a "Email Newsletter Preferences" custom multiselect field on your Sugar Contacts module. If you add the value "Investor Updates" as another option to your MailChimp Group or Sugar multiselect field, it will automatically add it as an option on the other side.
This can be one of the most difficult pieces to the integration. If you're having issues, definitely create a support case so we can help you out. Thanks!