Confusion about css coding standards for Html Email newsletter

[hotfuzz]

i am coding Email newsletters. i have seen some guidelines regarding Good email coding.. i want to ask about css code for Email newsletters for example its preffered to code inline css but for some free templates i found code like this \[code\] <style type="text/css"> body { color:#000; background-color:#fff; font-family:Arial, Helvetica, sansserif; text-align:center; } h2 { color:#2255DB; font-size:16px; margin-top:15px; margin-bottom:0px; } h2 a:link { text-decoration:none; } .footer { fontsize:11px; text-align:center; color:#2255DB; }// and son on </style>\[/code\]in body code for fotter is like \[code\] <p class="footer" style="color:#2255DB;"> footer...</footer>//again style tag\[/code\]and sometimes i found like this total inline styling .. \[code\] <span style="font-weight: bold; width: 525px;"> Lorem ipsum dolo </span><br><br>// and son on ,, \[/code\]Both the above mentioned codes are working fine in Email clients i have also seen standards from Campaign monitor etc, so i am confused which style is better .. should we use style in as in above mentioned code and or total inline coding , Please if someone can clear me about this ..it would be great favor EDIT : once coded is there any free service that can help to check if its valid code for mail clients ?