Monday, September 2, 2013

SMTP Server Configuration and Email Throttling

To send out an email campaign, you need to configure at least one SMTP server in BitFaster. If you  wish to speed up the process of sending an email campaign, you can use more than one SMTP server.

There is no limit on the number of SMTP servers you can define in BitFaster. BitFaster can automatically distribute the load amongst these servers when you start an email campaign.

Assuming that you have already defined one or more SMTP servers, follow the steps below to assign the server(s) in the New Email Campaign or Edit Email Campaign window:

  • Select SMTP/Message Settings tab (on the left)
  • Enter the mandatory fields – From Name and From Address
  • In the SMTP Server(s) list box, check/tick one or more SMTP servers
  • Add the Campaign (if you are done with all other settings) or save the changes if you are updating the campaign.

With this, BitFaster knows the SMTP servers that it has to use for sending out an email campaign. Now, you can tweak some of the settings to optimize delivery.

Click on the Options icon in the toolbar (or from the menu choose View > Options) to bring up the Options window. Now click on Mail Settings.

The Maximum Threads field is used to tell BitFaster the number of asynchronous connections it has to initiate with an SMTP Server. For example, if you specify 5 here, BitFaster will initiate 5 simultaneous connection to the SMTP Server and try sending all of them at the same time.

Please note that the threads you specify is per SMTP Server. If you choose to use 3 SMTP Servers, BitFaster will actually initiate 15 simultaneous connections (5 per server). The more threads you specify and the more SMTP servers you define and use, the faster will the mails get delivered.


Every email/hosting provider will have the following limitations applied:

  • Maximum threads per SMTP server
  • Maximum number of messages per hour
  • Maximum number of messages per day (24 hour cycle)
  • Make sure you keep this mind (verify them with your service provider) and then select the number of threads. BitFaster can support up to 100 threads per SMTP server.

The other important setting you can configure in BitFaster is Email Throttling. As mentioned above, your service provider can put an hourly restriction on the number of messages you can send per SMTP server.

Let’s take an example here so that you can understand how to configure BitFaster better.

  • No. of Emails to be sent: 5000
  • No. of SMTP Servers (or accounts): 3
  • Hourly limit (set by the service provider): 200 messages per SMTP server/account
  • Thread limit (set by the service provider): 10

Going by the above example, you can send a maximum of 600 messages per hour with 30 threads.

You can configure BitFaster as per the settings shown below for optimum results:

  • Maximum Threads: 5
  • Enable Auto Pause (Email Throttling): Check/Tick
  • Pause for: 45 minutes
  • After every: 500 messages

Please Note: Email Throttling is available only in BitFaster Professional.

The above configuration will tell BitFaster to initiate 15 simultaneous connections, send 500 messages and then wait/sleep for 45 minutes before it can pick up the next set of 500 email addresses. This means, that BitFaster will split your email list into 10 batches of 500 each.

Assuming that it takes 15 minutes to send out 500 messages, you are now in safe zone because BitFaster will wait for 45 minutes until it picks up the next set of 500 messages. That means you are sending only 500 messages per hour and you will never exceed your quota of 600 messages per hour. Your email campaign will take about 10 hours (or less) to complete the campaign based on all these assumptions.

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