What are these parameters in POST?

When I click on the "save" button, a request is sent to the server , this is an email from the Tinymce editor with pictures. The parameters{[5] are passed to the server at this point]}

-----------------------------28257400717280
Content-Disposition: form-data; name="act"

save_tmp
-----------------------------28257400717280
Content-Disposition: form-data; name="headers"

1|1|1
-----------------------------28257400717280
Content-Disposition: form-data; name="mail_body"

<p><img src="\&quot;file.1.png\&quot;" /><img src="\&quot;\\&quot;file.1.png\\&quot;\&quot;" /><img src="\&quot;\\&quot;\\\\&quot;\\\\\\\\&quot;\\\\\\\\\\\\\\\\&quot;file.1.png\\\\\\\\\\\\\\\\&quot;\\\\\\\\&quot;\\\\&quot;\\&quot;\&quot;" /><img src="\&quot;\\&quot;\\\\&quot;\\\\\\\\&quot;file.1.png\\\\\\\\&quot;\\\\&quot;\\&quot;\&quot;" /><img src="\&quot;\\&quot;\\\\&quot;file.1.png\\\\&quot;\\&quot;\&quot;" /></p>
-----------------------------28257400717280
Content-Disposition: form-data; name="attach"

-----------------------------28257400717280
Content-Disposition: form-data; name="hdir"

17.05.2018
-----------------------------28257400717280--

What are these parameters? and most importantly, how to fix them. near the file name, " and slashes are constantly substituted, I need to remove them so that it is

     <img src="file.1.jpg"> 

What? what line to look for in the scripts?

Here is the form

<form id="mce" name="mce">

               <table id="mheader" cellspacing="0" cellpadding="0"><tbody><tr><td id="msubj">
                Тема письма<br>
                <input id="msubj" type="text">
            </td><td id="mfromtxt">
                От кого<br>
                <input id="mfromtxt" type="text">
            </td><td id="mfrommail">
                E-mail отправителя<br>
                <input id="mfrommail" type="text">
            </td></tr></tbody></table>

            <div id="mceu_23" class="mce-tinymce mce-container mce-panel" hidefocus="1" tabindex="-1" role="application" style="visibility: hidden; border-width: 1px;"><div id="mceu_23-body" class="mce-container-body mce-stack-layout"><div id="mceu_24" class="mce-toolbar-grp mce-container mce-panel mce-stack-layout-item mce-first" hidefocus="1" tabindex="-1" role="group"><div id="mceu_24-body" class="mce-container-body mce-stack-layout"><div id="mceu_25" class="mce-container mce-toolbar mce-stack-layout-item mce-first" role="toolbar"><div id="mceu_25-body" class="mce-container-body mce-flow-layout"><div id="mceu_26" class="mce-container mce-flow-layout-item mce-first mce-btn-group" role="group"><div id="mceu_26-body"><div id="mceu_0" class="mce-widget mce-btn mce-first" tabindex="-1" aria-labelledby="mceu_0" role="button" aria-label="Source code"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-code"></i></button></div><div id="mceu_1" class="mce-widget mce-btn mce-last" tabindex="-1" aria-labelledby="mceu_1" role="button" aria-label="Preview"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-preview"></i></button></div></div></div><div id="mceu_27" class="mce-container mce-flow-layout-item mce-btn-group" role="group"><div id="mceu_27-body"><div id="mceu_2" class="mce-widget mce-btn mce-menubtn mce-first mce-btn-has-text" tabindex="-1" aria-labelledby="mceu_2" role="button" aria-haspopup="true"><button id="mceu_2-open" role="presentation" type="button" tabindex="-1"><span class="mce-txt">Формат</span> <i class="mce-caret"></i></button></div><div id="mceu_3" class="mce-widget mce-btn mce-menubtn mce-fixed-width mce-listbox mce-btn-has-text" tabindex="-1" aria-labelledby="mceu_3" role="button" aria-label="Font Sizes" aria-haspopup="true"><button id="mceu_3-open" role="presentation" type="button" tabindex="-1"><span class="mce-txt">Размер шрифта</span> <i class="mce-caret"></i></button></div><div id="mceu_4" class="mce-widget mce-btn mce-menubtn mce-fixed-width mce-listbox mce-last mce-btn-has-text" tabindex="-1" aria-labelledby="mceu_4" role="button" aria-label="Font Family" aria-haspopup="true"><button id="mceu_4-open" role="presentation" type="button" tabindex="-1"><span class="mce-txt">Шрифт</span> <i class="mce-caret"></i></button></div></div></div><div id="mceu_28" class="mce-container mce-flow-layout-item mce-last mce-btn-group" role="group"><div id="mceu_28-body"><div id="mceu_5" class="mce-widget mce-btn mce-first" tabindex="-1" aria-labelledby="mceu_5" role="button" aria-label="Horizontal line"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-hr"></i></button></div><div id="mceu_6" class="mce-widget mce-btn mce-menubtn" tabindex="-1" aria-labelledby="mceu_6" role="button" aria-label="Table" aria-haspopup="true"><button id="mceu_6-open" role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-table"></i> <i class="mce-caret"></i></button></div><div id="mceu_7" class="mce-widget mce-btn" tabindex="-1" aria-labelledby="mceu_7" role="button" aria-label="Insert/edit link"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-link"></i></button></div><div id="mceu_8" class="mce-widget mce-btn" tabindex="-1" aria-labelledby="mceu_8" role="button" aria-label="Remove link"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-unlink"></i></button></div><div id="mceu_9" class="mce-widget mce-btn mce-last" tabindex="-1" aria-labelledby="mceu_9" role="button" aria-label="Insert/edit image"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-image"></i></button></div></div></div></div></div><div id="mceu_29" class="mce-container mce-toolbar mce-stack-layout-item mce-last" role="toolbar"><div id="mceu_29-body" class="mce-container-body mce-flow-layout"><div id="mceu_30" class="mce-container mce-flow-layout-item mce-first mce-btn-group" role="group"><div id="mceu_30-body"><div id="mceu_10" class="mce-widget mce-btn mce-first" tabindex="-1" aria-labelledby="mceu_10" role="button" aria-label="Clear formatting"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-removeformat"></i></button></div><div id="mceu_11" class="mce-widget mce-btn" tabindex="-1" aria-labelledby="mceu_11" role="button" aria-label="Bold"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-bold"></i></button></div><div id="mceu_12" class="mce-widget mce-btn" tabindex="-1" aria-labelledby="mceu_12" role="button" aria-label="Italic"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-italic"></i></button></div><div id="mceu_13" class="mce-widget mce-btn mce-colorbutton" role="button" tabindex="-1" aria-haspopup="true" aria-label="Text color"><button role="presentation" hidefocus="1" type="button" tabindex="-1"><i class="mce-ico mce-i-forecolor"></i><span id="mceu_13-preview" class="mce-preview"></span></button><button type="button" class="mce-open" hidefocus="1" tabindex="-1"> <i class="mce-caret"></i></button></div><div id="mceu_14" class="mce-widget mce-btn mce-colorbutton mce-last" role="button" tabindex="-1" aria-haspopup="true" aria-label="Background color"><button role="presentation" hidefocus="1" type="button" tabindex="-1"><i class="mce-ico mce-i-backcolor"></i><span id="mceu_14-preview" class="mce-preview"></span></button><button type="button" class="mce-open" hidefocus="1" tabindex="-1"> <i class="mce-caret"></i></button></div></div></div><div id="mceu_31" class="mce-container mce-flow-layout-item mce-btn-group" role="group"><div id="mceu_31-body"><div id="mceu_15" class="mce-widget mce-btn mce-first" tabindex="-1" aria-labelledby="mceu_15" role="button" aria-label="Align left"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-alignleft"></i></button></div><div id="mceu_16" class="mce-widget mce-btn" tabindex="-1" aria-labelledby="mceu_16" role="button" aria-label="Align center"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-aligncenter"></i></button></div><div id="mceu_17" class="mce-widget mce-btn" tabindex="-1" aria-labelledby="mceu_17" role="button" aria-label="Align right"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-alignright"></i></button></div><div id="mceu_18" class="mce-widget mce-btn mce-last" tabindex="-1" aria-labelledby="mceu_18" role="button" aria-label="Justify"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-alignjustify"></i></button></div></div></div><div id="mceu_32" class="mce-container mce-flow-layout-item mce-btn-group" role="group"><div id="mceu_32-body"><div id="mceu_19" class="mce-widget mce-btn mce-splitbtn mce-menubtn mce-first" role="button" tabindex="-1" aria-label="Bullet list" aria-haspopup="true"><button type="button" hidefocus="1" tabindex="-1"><i class="mce-ico mce-i-bullist"></i></button><button type="button" class="mce-open" hidefocus="1" tabindex="-1"> <i class="mce-caret"></i></button></div><div id="mceu_20" class="mce-widget mce-btn mce-splitbtn mce-menubtn mce-last" role="button" tabindex="-1" aria-label="Numbered list" aria-haspopup="true"><button type="button" hidefocus="1" tabindex="-1"><i class="mce-ico mce-i-numlist"></i></button><button type="button" class="mce-open" hidefocus="1" tabindex="-1"> <i class="mce-caret"></i></button></div></div></div><div id="mceu_33" class="mce-container mce-flow-layout-item mce-last mce-btn-group" role="group"><div id="mceu_33-body"><div id="mceu_21" class="mce-widget mce-btn mce-first" tabindex="-1" aria-labelledby="mceu_21" role="button" aria-label="Decrease indent"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-outdent"></i></button></div><div id="mceu_22" class="mce-widget mce-btn mce-last" tabindex="-1" aria-labelledby="mceu_22" role="button" aria-label="Increase indent"><button role="presentation" type="button" tabindex="-1"><i class="mce-ico mce-i-indent"></i></button></div></div></div></div></div></div></div><div id="mceu_34" class="mce-edit-area mce-container mce-panel mce-stack-layout-item" hidefocus="1" tabindex="-1" role="group" style="border-width: 1px 0px 0px;"><iframe id="mce_0_ifr" allowtransparency="true" title="Текстовое поле. Нажмите ALT-F9 чтобы вызвать меню, ALT-F10 панель инструментов, ALT-0 для вызова помощи." style="width: 100%; height: 300px; display: block;" src="javascript:&quot;&quot;" frameborder="0"></iframe></div><div id="mceu_35" class="mce-statusbar mce-container mce-panel mce-stack-layout-item mce-last" hidefocus="1" tabindex="-1" role="group" style="border-width: 1px 0px 0px;"><div id="mceu_35-body" class="mce-container-body mce-flow-layout"><div id="mceu_36" class="mce-path mce-flow-layout-item mce-first"><div role="button" class="mce-path-item mce-last" data-index="0" tabindex="-1" id="mceu_36-0" aria-level="0">p</div></div><div id="mceu_37" class="mce-flow-layout-item mce-last mce-resizehandle"><i class="mce-ico mce-i-resize"></i></div></div></div></div></div><textarea id="mce_0" style="display: none;" aria-hidden="true"></textarea>

            <div id="mfiles"><span id="mfile"><span id="mfile_name" onclick="in_to(&quot;file.1.png&quot;)">file.1.png</span><a href="javascript:void(0);" onclick="fdel(&quot;file.1.png&quot;,&quot;delete&quot;);" title="Удалить">Х</a><input id="mfile_name" title="Прикрепить" value="file.1.png" type="checkbox"></span></div>

            <table width="100%" cellspacing="0" cellpadding="0"><tbody><tr><td width="50%">
                <input id="mfile" class="upload" accept=".doc,.pdf,.docx,.txt,.png,image/*" type="file">
            </td><td style="text-align: right;">
                <input id="mfile" class="save" value="Сохранить" type="button">&nbsp;&nbsp;&nbsp;
            </td><td style="text-align: right;">
                <input id="mfile" class="ready" value="Готово" type="button">
            </td></tr></tbody></table>

        </form>

Here is var_dump ($_POST) by clicking on the{[5] button]}

array(5) { ["act"]=> string(8) "save_tmp" ["headers"]=> string(59)     "Тестовое письмо|[email protected]|[email protected]" ["mail_body"]=> string(34) "
1" ["attach"]=> string(0) "" ["hdir"]=> string(10) "17.05.2018" }