What is the default interval time for batch emails?

Question

We are using EE's built-in communication tool to send out an initial email to all of the site's members letting them know about the new site design and functionality updates. I would like to batch process these 6000 emails. I have "Use Batch Mode" set to yes, and the number of emails per batch is set to 300.

Does anyone know what the default interval time is for batch emails in EE and whether or not it is customizable? I haven't been able to find it anywhere in the documentation. Thanks!

Disclaimer: I tried to push a service such as MailChimp in lieu of the built-in communicate tool, but that's not an option for us at this point in time.

Answer 1

In short it isn't configurable via EE as far as I know. It will automatically handled depending on latency between your server and SendGrid but SendGrid will have very high send rates as they're a dedicated SMTP provider. They don't seem to specify the rate limits but they do make mention of the factors that will impact delivery rates:

A local mail server, such as Postfix, is the most robust way to send email through SendGrid when configured to queue all email from your application and then relay the messages through SendGrid as a smart host. This has the least latency from your application’s perspective with the added benefit of handing your email off to a fault tolerant server. If internet connectivity between your servers and ours drops, a local mail server gracefully handles queuing and resending the email, as opposed to building that intelligence into your sending application.

Local mail servers also have advantages at high volume as they can use some of the more complex parts of the SMTP protocol, such as connection reuse and pipelining. With these techniques a mail server sends significantly more traffic in a given time than if you have individual scripts connecting for each message.