We have successfully developed a drip email campaign module for SugarCRM. This module allows sending emails tied to a particular campaign to users based on relative dates. Some of the most relevant features:

- Create Lead/Partner/Account, associate them with a campaign.
- Select this Lead/Partner/Account’s campaign start date
- Send first email to Lead/Partner/Account at start_date + x (where x is in days)
- Send second email to Lead/Partner/Account at start_date + y (where y is in days)
- Compatible with all SugarCRM types: OpenSource, Professional and Enterprise.

Each user on the same campaign could get email on different days — the email date is based on that user’s campaign start day, not on the calendar day of the year.

Check some screenshots of the module: