Some people like to have detailed email comments to their Magento customers.  Unfortunately, these email comment notifications and the comment history inside of the Magento history panel, do not show paragraphs or new lines.  This will show you how to fix this comment new line bug.

I am using a mac here, but a similar process can be done on a PC.

mkdir -p app/code/local/Mage/Adminhtml/controllers/Sales/
cp app/code/core/Mage/Adminhtml/controllers/Sales/OrderController.php app/code/local/Mage/Adminhtml/controllers/Sales/OrderController.php

What we are doing there is copying

app/code/core/Mage/Adminhtml/controllers/Sales/OrderController.php

to

app/code/local/Mage/Adminhtml/controllers/Sales/OrderController.php

so that our changes don't get overwritten in updates.

Now some code edits.  I am using Mavento 1.7 in this example, however this should work on other versions of magento.

Look around line 276 of the newly created file for:

$comment = trim(strip_tags($data['comment']));

We want to change that to:

$comment = nl2br(trim(strip_tags($data['comment'])));

That will make your paragraph marks show up as desired.

I hope this got your paragraphs inside of your Magento comments working, if so, please +1 and or like this post!