Why do my messages grow in size when I send them via AuthSMTP?
All emails grow in size when sent due to the encoding required to transport them across the Internet.
You may notice that when you send a message via AuthSMTP the size displayed in the history section of the Control Panel is bigger than the size of the message on your computer. This isn't unique to AuthSMTP, it happens to all emails sent over the Internet regardless of ISP, SMTP server, email program, message type or attachment type.
When the email and / or attachment is on your computer it is one single complete file, when you send the message via an SMTP service the email and any attachments have to be encoded so that they can be broken into smaller segments and transported across the Internet.
The percentage of growth will vary but could be as high as 50% with particular file types, typically we would expect an email with an attachment that is 10MB in size to grow to around 14MB when sent via email.
If you have any questions please contact us.