I received a Mail, because i tried to login from a new device. I noticed that your mails are not displayed correctly in Outlook.
1. <table width="500px" .... should be <table width="500" ...., so your table has the correct width. I don't understand why, but it works.
2. font-family:arial,verdana,sans-serif;color:#000;font-size:15px; needs to be in every table-td, because the font-format will not be inherited.
3. color:#000 should be color:#000000, Outlook does not like shortened color-codes