What to know about batch email delivery and throttling
The concept of throttling has been around since the very early days of email. Throttling refers to the limiting of sending or receiving of email messages; performance degradation in the form of slower sending or receiving is a typical outcome of throttling (throttling is different to capping).
Many ISP’s enforce throttling when thresholds of incoming email messages from a specific IP address are reached. As an example, in a Mailchimp class I was delivering yesterday one of the attendees mentioned that they have been sending mass emails via their ISP; If they send more than about 50 messages to the same domain then the messages sent to that domain would be returned as undelivered. What is likely happening in this instance is that the receiving server is set to limit the number of messages received from any one IP address during a short period of time (most likely to stop a mass number of spam email messages being received in a short space of time). The unexpected mass receiving of a large number of emails from the same IP address can be as the result of an incoming email bomb (which is unfortunately simple enough to initiate).
In some instances it’s possible to avoid meeting the receiving servers threshold limits by sending email messages in batches. This means that instead of sending to all your 1,000 subscribers at the same time, you’ll send 10 batches of 100 emails. This of course is usually a very time consuming way of sending email campaigns.
Why Mailchimp is better as mass email sending
Good email marketing services such as Mailchimp specialise in high deliverability; getting your message in front of the intended recipient. One of the things that Mailchimp does to circumvent having to send email messages in batches is to send any one campaign using multiple IP addresses that have been primed to have a good reputation. Mailchimp therefore doesn’t suffer from the issue where the receiving server identifies that too many emails are being received in a short space of time from the same IP address.
Should you be sending using batch email delivery
As mentioned in the first paragraph, Mailchimp has an option whereby you may have your email campaign sent in batches. This however is unnecessary for almost all but the very largest volume senders.
Using a service such as Mailchimp is far quicker and more reliable at sending email marketing than using Outlook with your ISP. Here in Australia some of the popular ISP’s have very low sending limits such as a maximum of 250 emails permitted to be sent a day. There are no maximum sending limits when using Mailchimp if you subscribe to a paid subscription.