I\'m sending an email from MS Outlook (2013) and it\'s working perfectly, but in the GMail app for Android (it also happens for iOS) there is a gap between lines (rows).
You already identified your problem, the reason behind your problem and a solution, which is stop using Outlook to send emails. Use a service or a software program that doesn't alter your code when you do a send.
Outlook, Gmail and just about every single email client will change your code when it renders it. Outlook will strip out things that don't work in Outlook. The same with Gmail. The best known example of this is how Gmail will strip out a sheet when it runs across an incompatible CSS value. You can use a service like Putsmail to test your work to see if the issue is Outlook or an issue with formatting.
If you are going to continue to pursue this path of frustration, at least use a properly formatted THIS CELL (TD) HAS TOP AND BOTTOM EXTRA SPACE WHEN RECEIVING FROM MS OUTLOOK THIS CELL (TD) HAS TOP AND BOTTOM EXTRA SPACE WHEN RECEIVING FROM MS OUTLOOK I use this same table structure without fail to successfully send emails. Good luck..