Dynamics 365: Delete Attachments from email messages

DeleteAttachments.cs

private static void DeleteAttachments(CrmServiceClient crmService)
{
    const bool testing = true;
    const int filesize = 0;
    const string actualend = "2023-12-31T00:00:00-06:00";
    const string operationDescription = testing ? "Retrieved" : "Deleting";

    var query = new QueryExpression("email")
    {
        Distinct = true,
    };

    // ReSharper disable once ConditionIsAlwaysTrueOrFalse
    if (testing)
    {
        query.TopCount = 25;
    }

    query.ColumnSet.AddColumns(
        "subject",
        "activityid");

    query.Criteria.AddCondition("actualend", ConditionOperator.OnOrBefore, actualend);

    var linkEntity = query.AddLink("activitymimeattachment", "activityid", "objectid");

    linkEntity.EntityAlias = "ag";

    linkEntity.Columns.AddColumn("activitymimeattachmentid");

    linkEntity.LinkCriteria.AddCondition("filesize", ConditionOperator.GreaterThan, filesize);

    var results = crmService.RetrieveMultiple(query);

    Console.WriteLine();
    Console.WriteLine("ATTACHMENT REMOVAL");
    Console.WriteLine($"\tFilesize greater than: {filesize}");
    Console.WriteLine($"\tOn or Before: {actualend}.");
    Console.WriteLine();

    if (results.Entities == null || results.Entities.Count == 0)
    {
        Console.WriteLine();
        Console.WriteLine("No attachment records were found using the above criteria.");
        Console.WriteLine();
        Console.Write("Press any key...");
        Console.ReadKey();

        return;
    }

    for (var index = 0; index < results.Entities.Count; index++)
    {
        var entity = results.Entities[index];
        var id = entity.GetAliasedAttributeValue<Guid>("ag.activitymimeattachmentid");

        Console.WriteLine($"{operationDescription}: {index + 1} of {results.Entities.Count}. ID: {id}");

        // ReSharper disable once ConditionIsAlwaysTrueOrFalse
        if (!testing)
        {
            crmService.Delete(ActivityMimeAttachment.EntityLogicalName, id);
        }
    }

    Console.WriteLine();
    Console.WriteLine();
    Console.Write("Processing complete. Press any key...");
    Console.ReadKey();
}