In order to provide the highest possible level of performance, our servers have the below restrictions when injecting messages.
- Your IP address must have a PTR (Reverse DNS) entry.
- Maximum of 10 simultaneous connections per account
- Maximum 500 recipients per message
- There is a limit of 50 messages per connection and sending multiple messages per connection is encouraged.
- Messages larger than 128K are not DKIM signed.
- Messages with an HTML body size greater than 128K are not open/click tracked. The
- HTML body size is just the total byte count of of the HTML markup and does not include plain text bodies, attachments, images, or any other message content.
- Messages sizes are limited to 30MB.
If you attempt more than 10 connections you will receive the following error:
421 4.4.5 - Too many connections from your host