Is there a way to prevent Content Builder from altering HTML pasted into an HTML block?

Question

We are attempting to migrate some content blocks from Classic Content to Content Builder in anticipation of Classic Content going away. This content is basically table rows that get dynamically pulled into an HTML Paste email. We have noticed two very problematic things happening. First, when we paste the rows into the editor, the editor alters the HTML. It completely removes entire sections - like a very bad magic trick. Second, even if we paste, save and immediately try to generate an email with that content block, it breaks the surrounding HTML. It seems that Content Building is embellishing our HTML and causing the table in our email to no longer work. Is there any way to pull in table rows HTML without getting any "extras"? Code Snippets won't work since these are dynamic emails and the content inserted varies by the week.

Before:

<!-- Spacer --> 
                <tr>
                   <td width="12" height="12" border="0" cellspacing="0" cellpadding="0" style="margin:0; width:12; height:12; background-color:#FFFFFF">
                   </td>
                </tr>
                <!-- /Spacer -->
   <tr>
  <td>
   <table align="center" width="600" cellpadding="0" cellspacing="0" border="0" style="margin:0;-webkit-text-size-adjust:100%; -ms-text-size-adjust:100%;background-color:#f0f0f0;">
    <tr>
     <td style="line-height:0px; mso-line-height-rule:exactly;"><a href="https://www.myecp.com/HtmlPages/CP_MilStartCard"><img src="http://image.email.shopmyexchange.com/lib/fe9612727265077874/m/11/d04308a1-4803-487d-8476-24f99e97ee07.jpg?b=1520520661000" width="600" height="64" alt="Earn Points with Military Star" style="display:block; margin:0; border:0;
      background-color:#f0f0f0; color:#C11A2C;
      font-size:11px; font-weight:bold;" /></a>
     </td>                                    
    </tr>
   </table>
  </td>
 </tr>

AFTER:

                <!-- /Spacer -->




 <table align="center" width="600" cellpadding="0" cellspacing="0" border="0" style="margin:0;-webkit-text-size-adjust:100%; -ms-text-size-adjust:100%;background-color:#f0f0f0;">
    <tr>
     <td style="line-height:0px; mso-line-height-rule:exactly;"><a href="https://www.myecp.com/HtmlPages/CP_MilStartCard"><img src="http://image.email.shopmyexchange.com/lib/fe9612727265077874/m/11/d04308a1-4803-487d-8476-24f99e97ee07.jpg?b=1520520661000" width="600" height="64" alt="Earn Points with Military Star" style="display:block; margin:0; border:0;
      background-color:#f0f0f0; color:#C11A2C;
      font-size:11px; font-weight:bold;"></a>
     </td>                                    
    </tr>
   </table>

Answer 1

The reason the spacer table is disappearing is because inside the eyes of SFMC editor (along with TinyMCE - which is used to handle the HTML processing from the WYSIWYG) it has no content, so it doesn't exist. Your spacer table needs some sort of entity in it. Usually what I do in these situations is as follows:

<table><tr><td><!--spacer-->&nbsp;<!--endspacer--></td></tr></table>

When set this way it retains the table as it has 'content' inside the table. If it thinks the table is empty, it will remove the 'excess' code when running its processor.

It does work when you use just the non-breaking space entity, but I find more success utilizing the comments around it too - sometimes just the nbsp will disappear as well.

As for the disappearing table row and table data tags, this can easily be solved via Code Snippet. I am not sure why in your use case you state it is not an option. You can utilize it inside an ampscript call utilizing the ID, same as a regular content block and it is selectable via Dynamic Content block.

Inside the HTML block, it is viewing the content as syntaxually incorrect as each block is viewed as a whole piece, not a snippet. In order to not break the block, it removes the invalid content. To get around this, you can add an if statement based on an impossibility that opens and closes a table tag at beginning/end to trick it into thinking it is valid.

I know this is not a long term solution, but for a quick fix this should do the trick if code snippets are not an option.

E.g. %%[ if 1 = 2 THEN]%% <table> %%[ENDIF]%%

%%[ if 1 = 2 THEN]%% </table> %%[ENDIF]%%

Full sample:

<!-- Spacer --> 
%%[ if 1 = 2 THEN]%% <table>  %%[ENDIF]%%
                <tr>
                   <td width="12" height="12" border="0" cellspacing="0" cellpadding="0" style="margin:0; width:12; height:12; background-color:#FFFFFF">
                   </td>
                </tr>
                <!-- /Spacer -->
   <tr>
  <td>
   <table align="center" width="600" cellpadding="0" cellspacing="0" border="0" style="margin:0;-webkit-text-size-adjust:100%; -ms-text-size-adjust:100%;background-color:#f0f0f0;">
    <tr>
     <td style="line-height:0px; mso-line-height-rule:exactly;"><a href="https://www.myecp.com/HtmlPages/CP_MilStartCard"><img src="http://image.email.shopmyexchange.com/lib/fe9612727265077874/m/11/d04308a1-4803-487d-8476-24f99e97ee07.jpg?b=1520520661000" width="600" height="64" alt="Earn Points with Military Star" style="display:block; margin:0; border:0;
      background-color:#f0f0f0; color:#C11A2C;
      font-size:11px; font-weight:bold;"></a>
     </td>                                    
    </tr>
   </table>
  </td>
 </tr>
%%[ if 1 = 2 THEN]%% </table>  %%[ENDIF]%%

Another solution is to store the snippets inside of a data extension, but then you can run into issues with format, etc. that can cause corruption of data and incorrect display.