Probably my naivety, but if there's a loop putting the photos into an email, why can't the caption run after each loop? I'm not saying I'm a pro, but I've experience of setting up email from my time at the NEC and we simply couldn't have created emails like this if we'd have had to do it separately.
Sadly I've taken on two clients who take their images in emails, I can't have the caption as a watermark as it's not what they want, so on Saturday when sending one of the clients photos from a rugby match, I had to create 37 emails and send them over separately, so they could see the captions.
I know PM creates the emails for me, but it isn't very professional to send so many, and this is rugby - last years Ironman saw 174 photos submitted to local news.