Tcl
Create HTML Email Reply

The goal of this example is to create a new HTML body where the new reply HTML is at the top, and the original HTML body is below.
The .eml files for this example are available at HTML Reply Email Samples (.eml)
Note: This is only one of a million ways to do it..
Chilkat Tcl Downloads

Download Chilkat for Tcl
Tcl

load ./chilkat.dll

set success 0

set email [new_CkEmail]

# To create this example, I used Mozilla Thunderbird (with a GMail accont)
# to first send a simple HTML email to my chilkatsoft.com email address.  I then 
# used Thunderbird to reply with more HTML.
# I then saved both emails as .eml files.  These are available at
# http://chilkatdownload.com/example_data/htmlreplyemail.zip

# Load the .eml for the 1st email that was received. This is the original
# HTML email before the reply HTML is added.
set success [CkEmail_LoadEml $email "qa_data/eml/receivedHtmlEmail.eml"]
if {$success != 1} then {
    puts [CkEmail_lastErrorText $email]
    delete_CkEmail $email
    exit
}

# If this email doesn't have an HTML body, then do something else...
# (that's for another example maybe?)
if {[CkEmail_HasHtmlBody $email] == 0} then {
    puts "Email does not have an HTML body.."
    delete_CkEmail $email
    exit
}

# Get the HTML body in a StringBuilder..
set sbHtml [new_CkStringBuilder]

CkStringBuilder_Append $sbHtml [CkEmail_getHtmlBody $email]

# The HTML body contains this:
# <html><head>
# <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
#   </head>
#   <body bgcolor="#FFFFFF" text="#000000">
#     <font face="Calibri"><br>
#       This is a test <font color="#3366ff"><i>HTML email</i></font>...<br>
#       <br>
#       <br>
#     </font>
#   </body>
# </html>

# Make sure the BODY tags are lowercase.
set numReplaced [CkStringBuilder_Replace $sbHtml "<BODY" "<body"]
set numReplaced [CkStringBuilder_Replace $sbHtml "</BODY" "</body"]

# Get the HTML within the "body" open/close tags
set sbBodyContent [new_CkStringBuilder]

CkStringBuilder_Append $sbBodyContent [CkStringBuilder_getAfterBetween $sbHtml "<body" ">" "</body>"]

# Replace what we just extracted with a marker..
set numReplaced [CkStringBuilder_Replace $sbHtml [CkStringBuilder_getAsString $sbBodyContent] "TO_BE_UPDATED"]

# Create a template for the new body:
set sbTemplate [new_CkStringBuilder]

set bCrlf 1
CkStringBuilder_AppendLine $sbTemplate "REPLY_HTML_CONTENT" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "<br>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "<div class=\"moz-signature\">Best Regards,<br>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "  John Smith<br>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "  Chilkat Software, Inc.<br>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "  <p>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "    <a href=\"https://twitter.com/chilkatsoft\">Follow Chilkat on" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "      Twitter</a>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "  </p>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "</div>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "<div class=\"moz-cite-prefix\">On 2/8/2017 4:25 PM, Chilkat Support" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "  wrote:<br>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "</div>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "<blockquote>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "ORIGINAL_BODY_CONTENT" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "</blockquote>" $bCrlf
CkStringBuilder_AppendLine $sbTemplate "<br>" $bCrlf

# Replace the markers in the template with actual HTML.
# First our reply HTML:
set myHtmlReplyBody "This is my <font color=\"#6600cc\"><b>reply HTML</b></font><br>"
set numReplaced [CkStringBuilder_Replace $sbTemplate "REPLY_HTML_CONTENT" $myHtmlReplyBody]

# Now for the original HTML body content:
set numReplaced [CkStringBuilder_Replace $sbTemplate "ORIGINAL_BODY_CONTENT" [CkStringBuilder_getAsString $sbBodyContent]]

# Insert into sbHtml:
set numReplaced [CkStringBuilder_Replace $sbHtml "TO_BE_UPDATED" [CkStringBuilder_getAsString $sbTemplate]]

# Use sbHtml as the new HTML body..
CkEmail_SetHtmlBody $email [CkStringBuilder_getAsString $sbHtml]

# Examine the result HTML.
puts [CkStringBuilder_getAsString $sbHtml]

# Save the email.
CkEmail_SaveEml $email "qa_output/emailWithUpdatedHtmlBody.eml"

# Note: To finish creating the reply email, modify the To/From/CC headers,
# the subject, etc.  You may also with to iterate over the headers (from 1 to NumHeaderFields)
# and selectively remove all except the particular headers you wish to keep.
# You should keep: MIME-Version, Content-Type, Message-ID.  Chilkat will automaticaly
# generate and replace the Message-ID at the time of sending.  You'll want to replace
# the Date header with the current date/time.
# 

delete_CkEmail $email
delete_CkStringBuilder $sbHtml
delete_CkStringBuilder $sbBodyContent
delete_CkStringBuilder $sbTemplate