Problem: You want to send emal notifications with file attachments from your Jira, however, your email server doesn't handle mails where attachments exceed specific size. You want to email them unless the total size doesn't exceed specific value.
Solution: Use the following template example as reference
Conditional sending of attachments
#set ($totalLength = 0)
#foreach ($att in $issue.fields.attachment)
#set($totalLength = $totalLength + $att.size)
#end
#if ($totalLength < 10000000)
#foreach ($att in $issue.lastcomment.attachments)
$jirassimo.includeAttachment($att.id)
#end
#else
Attachments are too large for sending with email ($totalLength), please download them from Jira
#end
