diff --git a/addons/snailmail/models/snailmail_letter.py b/addons/snailmail/models/snailmail_letter.py
index 5d5d7ee8f71..53267c36538 100644
--- a/addons/snailmail/models/snailmail_letter.py
+++ b/addons/snailmail/models/snailmail_letter.py
@@ -4,7 +4,7 @@ import re
 import base64
 import io
 
-from PyPDF2 import PdfFileReader, PdfFileMerger
+from PyPDF2 import PdfFileReader, PdfFileMerger, PdfFileWriter
 from reportlab.platypus import Frame, Paragraph, KeepInFrame
 from reportlab.lib.units import mm
 from reportlab.lib.pagesizes import A4
@@ -150,6 +150,7 @@ class SnailmailLetter(models.Model):
             if (paperformat.format == 'custom' and paperformat.page_width != 210 and paperformat.page_height != 297) or paperformat.format != 'A4':
                 raise UserError(_("Please use an A4 Paper format."))
             pdf_bin, unused_filetype = self.env['ir.actions.report'].with_context(snailmail_layout=not self.cover, lang='en_US')._render_qweb_pdf(report, self.res_id)
+            pdf_bin = self._overwrite_margins(pdf_bin)
             if self.cover:
                 pdf_bin = self._append_cover_page(pdf_bin)
             attachment = self.env['ir.attachment'].create({
@@ -471,3 +472,49 @@ class SnailmailLetter(models.Model):
         out_buff = io.BytesIO()
         merger.write(out_buff)
         return out_buff.getvalue()
+
+    def _overwrite_margins(self, invoice_bin: bytes):
+        """
+        Fill the margins with white for validation purposes.
+        """
+        pdf_buf = io.BytesIO()
+        canvas = Canvas(pdf_buf, pagesize=A4)
+        canvas.setFillColorRGB(255, 255, 255)
+        page_width = A4[0]
+        page_height = A4[1]
+
+        # Horizontal Margin
+        hmargin_width = page_width
+        hmargin_height = 5 * mm
+
+        # Vertical Margin
+        vmargin_width = 5 * mm
+        vmargin_height = page_height
+
+        # Bottom left square
+        sq_width = 15 * mm
+
+        # Draw the horizontal margins
+        canvas.rect(0, 0, hmargin_width, hmargin_height, stroke=0, fill=1)
+        canvas.rect(0, page_height, hmargin_width, -hmargin_height, stroke=0, fill=1)
+
+        # Draw the vertical margins
+        canvas.rect(0, 0, vmargin_width, vmargin_height, stroke=0, fill=1)
+        canvas.rect(page_width, 0, -vmargin_width, vmargin_height, stroke=0, fill=1)
+
+        # Draw the bottom left white square
+        canvas.rect(0, 0, sq_width, sq_width, stroke=0, fill=1)
+        canvas.save()
+        pdf_buf.seek(0)
+
+        new_pdf = PdfFileReader(pdf_buf)
+        curr_pdf = PdfFileReader(io.BytesIO(invoice_bin))
+        out = PdfFileWriter()
+        for page in curr_pdf.pages:
+            page.mergePage(new_pdf.getPage(0))
+            out.addPage(page)
+        out_stream = io.BytesIO()
+        out.write(out_stream)
+        out_bin = out_stream.getvalue()
+        out_stream.close()
+        return out_bin