Hi Everyone,

This is the first trigger that I've written for one of our teams. I've reviewed other related community posts which have helped me get to this point but now I'm at a wall and would like some assistance. 

*When customers are emailed and the sales rep includes the email-to-salesforce bcc address, the email is added to the 'Activity History' of the 'Account' as a 'Task'. The trigger will look at all new Tasks and if they are 1) of type 'Email' and 2) related to customer accounts then it will update a custom field 'CS Last Contact Date' with the created date of the task.

Things I've noticed from the logs:
A) Tasks created through the email-to-salesforce feature and assigned to Accounts don't have whatIds. Anyone know why this is?
B) The trigger doesn't throw any errors

trigger UpdateAccountLastCSContactDate on Task (after insert, after update) {

    
    /*Set of whatIds for objects that have tasks */
    Set<String> whatIDs = new Set<String>();
    for (Task t : Trigger.new) {
            whatIDs.add(t.whatID);
    }

    /*List of customer accounts that have tasks */
    List<Account> customerAccounts = [SELECT Id, Type, CS_Last_Contact_Date__c FROM Account WHERE Type = 'Customer'];
    
    /*Create map of Email Task <-> Related Object*/
    Map<String, Task> taskMap = new Map<String, Task>();
    for (Task t : Trigger.new){
        if (t.type == 'Email'){
            taskMap.put(t.whatID, t);   
        }
    }
    
    for (Account customerAcct : customerAccounts){
        /*if customer account id is in the taskmap then see if last contact date is less than task created date */
        if (taskMap.containsKey(customerAcct.Id)){ 
            if (taskMap.get(customerAcct.Id).CS_Contact_Date__c != NULL){
                if (customerAcct.CS_Last_Contact_Date__c < taskMap.get(customerAcct.Id).CS_Contact_Date__c){
                    /*sets last contact date to the created date of the task */
                    customerAcct.CS_Last_Contact_Date__c = taskMap.get(customerAcct.Id).CS_Contact_Date__c;
                }   
            }
        }
    }
    update customerAccounts;
}

Any help is GREATLY appreciated. Thanks,
Thomas