Notifications from the site

Is there a website online store.When buying on the website receive notification in the mail about the purchase and payment to the client.Also email the site administrator about the ordering of goods and payment.

Began to receive duplicate messages clients and administrator in large quantity.The order is one,a notification about purchase and payment, the client can come in 15 pieces and the same number to the administrator.Sometimes immediately ,sometimes with an interval.

You need to fix that duplicate messages do not come.

Initially the site was created with Tilda,but then from there downloaded and installed on another hosting and worked there

Messages go through phpmailer