Amazon SES: Message sending failed - The following SMTP error was encountered: 552 5.3.4 Message is too long

I was send mail with 7MB attachment file then I got below error. How can I solve it?

220 email-smtp.amazonaws.com ESMTP SimpleEmailService-d-8ND3U1R22 5Eg0poz3kAZNziS4R0Qn
hello: 250-email-smtp.amazonaws.com
250-8BITMIME
250-SIZE 10485760
250-STARTTLS
250-AUTH PLAIN LOGIN
250 Ok
starttls: 220 Ready to start TLS
hello: 250-email-smtp.amazonaws.com
250-8BITMIME
250-SIZE 10485760
250-STARTTLS
250-AUTH PLAIN LOGIN
250 Ok
from: 250 Ok
to: 250 Ok
data: 354 End data with .
552 5.3.4 Message is too long.
The following SMTP error was encountered: 552 5.3.4 Message is too long.
Unable to send email using PHP SMTP. Your server might not be configured to send mail using this method.