Notifications

Why don't I get any notifications of new emails despite setting it up to do so. Have 2 accounts G Mail and BT Internet Mail

My way around is that I have a Yahoo app that I can load the email accounts onto and that notifies me when i have new mails but i don't like and don't use that app So I can then go to the mail manager I do like Spark and read the mails But that app wont give me notifications. Just would like a simple notification on my iPhone and iPad that tells me i have new mail.