PHP solution for sending excessive email content-php Tutorial

If the PHP mail content is too large to be sent, the Ecshop secondary development site is used. When the Mail content is too large, the Mail will fail to be sent (stmp )? Please kindly advise ------ solution ------------------ change the execution time to a larger value and try ------ solution -------------------- change the execution time. you obviously failed to send an email that is too long than the PHP content.
When Ecshop secondary development site is used, when there are too many emails, the Mail will fail to be sent (stmp )? Expert advice

------ Solution --------------------
Try to increase the execution time
------ Solution --------------------
Change execution time
You obviously sent emails more than the execution time.