trigger EmailToTask on EmailMessage (after insert) {
list<Task> lstTask          = new list<Task>();
map<String,Id> mapEmail     = new map<String,Id>();
map<String,Id> mapWorkEmail = new map<String,Id>();
map<String,Id> mapHomeEmail = new map<String,Id>();

for(Contact con: [SELECT Id,Email,npe01__WorkEmail__c,npe01__HomeEmail__c FROM Contact]){
    if(string.isNotBlank(con.Email))
        mapEmail.put(con.Email,con.Id);
    if(string.isNotBlank(con.npe01__WorkEmail__c))
        mapWorkEmail.put(con.npe01__WorkEmail__c,con.Id);
    if(string.isNotBlank(con.npe01__HomeEmail__c))
        mapHomeEmail.put(con.npe01__HomeEmail__c,con.Id);
}

for (EmailMessage e : Trigger.new) {
   if (e.RelatedToId != NULL
   && (mapEmail <> NULL && !mapEmail.isEmpty()
       || mapWorkEmail <> NULL && !mapWorkEmail.isEmpty()
       || mapHomeEmail <> NULL && !mapHomeEmail.isEmpty())
      ) {
       Task t =  new Task();
       t.ActivityDate  = date.today();
       t.Description   = e.TextBody;
       t.Move_Type__c  = 'Personal Note/Email from Donor';
       t.Priority      = 'Normal';
       t.Status        = 'Completed';
       t.Subject       = e.Subject;
       t.WhatId        = e.RelatedToId;
       if(mapEmail.containsKey(e.ToAddress)){
            t.WhoId = mapEmail.get(e.ToAddress);
       }
       else if(mapWorkEmail.containsKey(e.ToAddress )){
            t.WhoId = mapWorkEmail.get(e.ToAddress);
       }
         else if(mapHomeEmail.containsKey(e.ToAddress )){
            t.WhoId = mapHomeEmail.get(e.ToAddress);
       }
       lstTask.add(t);
    }
}
if(lstTask <> NULL && !lstTask.isEmpty()){
    insert lstTask;
}}

@isTest
 public with sharing class TestEmailTrigger {

@isTest static void test_method_c() {
     Account a = new Account();
     a.Name  = 'Bob Smith Household';
     insert a;

     Contact c = new Contact();
     c.lastname = 'Smith';
     c.FirstName = 'Bob';
     c.AccountId = a.Id;
     c.npe01__HomeEmail__c = 'bob.test@gmail.com';
     c.npe01__WorkEmail__c = 'bob.test+5@gmail.com';
     c.Email = NULL;
     c.npe01__Preferred_Email__c = 'Work';
     insert c;

    EmailMessage e = new EmailMessage();
    e.BccAddress            = 'reporting@foodcorps.org';
    e.FromAddress           = 'reporting@foodcorps.org';
    e.FromName              = 'Medhanie Habte';
    e.MessageDate           = datetime.now();
    e.MessageIdentifier     = '';
    e.Status                = '3';
    e.Subject               = 'test';
    e.TextBody              = 'test';
    e.RelatedToId           = c.AccountId;
    e.ToAddress             = 'bob.test@gmail.com';
    e.ValidatedFromAddress  = 'reporting@foodcorps.org';
    insert e;

   Task t =  new Task();
   t.ActivityDate  = date.today();
   t.Description   = e.TextBody;
   t.Move_Type__c  = 'Personal Note/Email from Donor';
   t.Priority      = 'Normal';
   t.Status        = 'Completed';
   t.Subject       = e.Subject;
   t.WhatId        = e.RelatedToId;
   t.WhoId         = c.Id;
   insert t;
 }

@isTest static void test_method_b() {
     Account a = new Account();
     a.Name  = 'Bob Smith Household';
     insert a;

     Contact c = new Contact();
     c.lastname = 'Smith';
     c.FirstName = 'Bob';
     c.AccountId = a.Id;
     c.npe01__HomeEmail__c = '';
     c.npe01__WorkEmail__c = 'bob.test+5@gmail.com';
     c.Email = NULL;
     c.npe01__Preferred_Email__c = 'Work';
     insert c;

    EmailMessage e = new EmailMessage();
    e.BccAddress            = 'reporting@foodcorps.org';
    e.FromAddress           = 'reporting@foodcorps.org';
    e.FromName              = 'Medhanie Habte';
    e.MessageDate           = datetime.now();
    e.MessageIdentifier     = '';
    e.Status                = '3';
    e.Subject               = 'test';
    e.TextBody              = 'test';
    e.RelatedToId           = c.AccountId;
    e.ToAddress             = 'bob.test+5@gmail.com';
    e.ValidatedFromAddress  = 'reporting@foodcorps.org';
    insert e;

   Task t =  new Task();
   t.ActivityDate  = date.today();
   t.Description   = e.TextBody;
   t.Move_Type__c  = 'Personal Note/Email from Donor';
   t.Priority      = 'Normal';
   t.Status        = 'Completed';
   t.Subject       = e.Subject;
   t.WhatId        = e.RelatedToId;
   t.WhoId         = c.Id;
   insert t;
 }
@isTest static void test_method_d() {
     Account a = new Account();
     a.Name  = 'Bob Smith Household';
     insert a;

     Contact c = new Contact();
     c.lastname = 'Smith';
     c.FirstName = 'Bob';
     c.AccountId = a.Id;
     c.npe01__HomeEmail__c = 'bob.test+5@gmail.com';
     c.npe01__WorkEmail__c = NULL;
     c.Email = NULL;
     c.npe01__Preferred_Email__c = 'Work';
     insert c;

    EmailMessage e = new EmailMessage();
    e.BccAddress            = 'reporting@foodcorps.org';
    e.FromAddress           = 'reporting@foodcorps.org';
    e.FromName              = 'Medhanie Habte';
    e.MessageDate           = datetime.now();
    e.MessageIdentifier     = '';
    e.Status                = '3';
    e.Subject               = 'test';
    e.TextBody              = 'test';
    e.RelatedToId           = c.AccountId;
    e.ToAddress             = 'bob.test+5@gmail.com';
    e.ValidatedFromAddress  = 'reporting@foodcorps.org';
    insert e;

   Task t =  new Task();
   t.ActivityDate  = date.today();
   t.Description   = e.TextBody;
   t.Move_Type__c  = 'Personal Note/Email from Donor';
   t.Priority      = 'Normal';
   t.Status        = 'Completed';
   t.Subject       = e.Subject;
   t.WhatId        = e.RelatedToId;
   t.WhoId         = c.Id;
   insert t;} @isTest static void test_method_e() {
     Account a = new Account();
     a.Name  = 'Bob Smith Household';
     insert a;

     Contact c = new Contact();
     c.lastname = 'Smith';
     c.FirstName = 'Bob';
     c.AccountId = a.Id;
     c.npe01__HomeEmail__c = 'bob.test@gmail.com';
     c.npe01__WorkEmail__c = 'bob.test+5@gmail.com';
     c.Email = 'bob.test@aoltv.com';
     c.npe01__Preferred_Email__c = 'Work';
     insert c;

    EmailMessage e = new EmailMessage();
    e.BccAddress            = 'reporting@foodcorps.org';
    e.FromAddress           = 'reporting@foodcorps.org';
    e.FromName              = 'Medhanie Habte';
    e.MessageDate           = datetime.now();
    e.MessageIdentifier     = '';
    e.Status                = '3';
    e.Subject               = 'test';
    e.TextBody              = 'test';
    e.RelatedToId           = c.AccountId;
    e.ToAddress             = 'bob.test@gmail.com';
    e.ValidatedFromAddress  = 'reporting@foodcorps.org';
    insert e;

   Task t =  new Task();
   t.ActivityDate  = date.today();
   t.Description   = e.TextBody;
   t.Move_Type__c  = 'Personal Note/Email from Donor';
   t.Priority      = 'Normal';
   t.Status        = 'Completed';
   t.Subject       = e.Subject;
   t.WhatId        = e.RelatedToId;
   t.WhoId         = c.Id;
   insert t;}}

|| mapWorkEmail <> NULL && !mapWorkEmail.isEmpty()
       || mapHomeEmail <> NULL && !mapHomeEmail.isEmpty())