I'm encountering an issue with a guest site user receiving this error: " Insert failed. First exception on row 0; first error: TEMPLATE_NOT_FOUND, The record couldn't be saved because it triggered an email alert that failed. Please contact salesforce.com Customer Support". I've narrowed down the issue to merge fields on an email template causing the problem. Seems the guest site user somehow doesn't have access to the records being used as merge fields. The sharing settings for these objects are set to "Public Read/Write" access. I also tried adding a "Guest user access, based on criteria" sharing rule granting access to all records based on criteria that would hold true for any record. ANy idea how I may be able to fix this issue?