Email marketing is developing as a common means of online marketing for many companies and products. In this marketing campaign, bulk emails are sent out to large numbers of people so that the message regarding the product or the company reaches out to masses on a large scale. But have you ever given a thought to the thing that how emails are sent and how are that received on the other end. All this is possible through the efficient working of a SMTP relay server. Without proper SMTP service, it is neither possible to send out emails on that bulk scale nor is it possible to get reply emails in the inbox.When an email is sent out from a person’s email account, a connection from that server is made with another server that is related to the recipient’s email address. When both the servers are connected and the receiver’s email id is confirmed, then the email is delivered in the recipient’s inbox. The process of the email passing through a SMTP relay server just takes fractions of seconds before it gets delivered. If by chance the SMTP service gets hampered, emails might not be delivered to the respective email addresses. This is the reason that most of the companies that deal with email marketing keep backup servers so that work does not stop even if there is breakdown in one email server.There are many instances where the SMTP relay services might undergo breakdown due to overloading and overburdening of emails that are being sent. Usually when an email marketing company sends bulk mails and start getting replies in return, they start sending more numbers of emails to various people globally. It has been seen and reported that the success rates of email marketing is quite high. This is because many people reply to the emails that have come in their inbox. On getting replies it is obvious that the companies increase sending the numbers of mails. This leads to overloading of the servers and after some time it breaks down.SMTP service is very important for any system that deals with the sending and receiving of emails. It should be kept in mind that they should not be overloaded in any case as that might hamper the entire process of email communication. Proper maintenance of the server is also required from time to time so that there are no problems in its functioning.