How to get all contacts of an Account and build an email List in MS Dynamics CRM?

Question

I've an account Id, and would like to get the collection of contacts under the account to build an email list.

---

    //build up Email
    private Email BuildEmail(ActivityParty allcontacts){.... build my emailhere}

    private List<Entity> GetAllContactsFromAccountId(Guid accountId, List<Entity> toList)
    {          

        //how can I get all the contacts here
        foreach (Entity contact in Account.Contact.Entities)//????
        {
            Entity activityParty = new Entity("activityparty");
            activityParty["partyid"] = new EntityReference("??", e.Id);

            if (toList.Any(t => t.GetAttributeValue<EntityReference>("partyid").Id == e.Id)) continue;

            toList.Add(activityParty);
        }

        return toList;
    }

Answer 1

You can find the Account key "parentcustomerid" in contact entity. you can get contact collection by account id as below.

  private EntityCollection getContactByAccountId(IOrganizationService service, Guid accountId)
    {
        QueryExpression query = new QueryExpression("contact");
        query.ColumnSet = new ColumnSet(new string[] { "contactid", "fullname" });
        query.Criteria.AddCondition(new ConditionExpression("parentcustomerid", ConditionOperator.Equal, accountId))
        return service.RetrieveMultiple(query);
    }