diff --git a/htdocs/core/class/html.formmail.class.php b/htdocs/core/class/html.formmail.class.php
index 0c9a1b2531a..5998822a704 100644
--- a/htdocs/core/class/html.formmail.class.php
+++ b/htdocs/core/class/html.formmail.class.php
@@ -781,7 +781,11 @@ class FormMail extends Form
 					} elseif ($this->withmaindocfile == -1) {
 						$out .= '<input type="checkbox" id="addmaindocfile" name="addmaindocfile" value="1" checked="checked" />';
 					}
-					$out .= ' <label for="addmaindocfile">'.$langs->trans("JoinMainDoc").'.</label><br>';
+					if (!empty($conf->global->MAIL_MASS_ACTION_ADD_LAST_IF_MAIN_DOC_NOT_FOUND)) {
+						$out .= ' <label for="addmaindocfile">'.$langs->trans("JoinMainDocOrLastGenerated").'.</label><br>';
+					} else {
+						$out .= ' <label for="addmaindocfile">'.$langs->trans("JoinMainDoc").'.</label><br>';
+					}
 				}
 
 				if (is_numeric($this->withfile)) {
diff --git a/htdocs/langs/en_US/main.lang b/htdocs/langs/en_US/main.lang
index b39124c7c53..530f3b6af0e 100644
--- a/htdocs/langs/en_US/main.lang
+++ b/htdocs/langs/en_US/main.lang
@@ -621,6 +621,7 @@ MonthVeryShort11=N
 MonthVeryShort12=D
 AttachedFiles=Attached files and documents
 JoinMainDoc=Join main document
+JoinMainDocOrLastGenerated=Send the main document or the last generated one if not found
 DateFormatYYYYMM=YYYY-MM
 DateFormatYYYYMMDD=YYYY-MM-DD
 DateFormatYYYYMMDDHHMM=YYYY-MM-DD HH:SS
@@ -1172,4 +1173,4 @@ AddLineOnPosition=Add line on position (at the end if empty)
 ConfirmAllocateCommercial=Assign sales representative confirmation
 ConfirmAllocateCommercialQuestion=Are you sure you want to assign the %s selected record(s)?
 CommercialsAffected=Sales representatives affected
-CommercialAffected=Sales representative affected
\ No newline at end of file
+CommercialAffected=Sales representative affected
diff --git a/htdocs/langs/fr_FR/main.lang b/htdocs/langs/fr_FR/main.lang
index 12778f337dd..53ff7d545b3 100644
--- a/htdocs/langs/fr_FR/main.lang
+++ b/htdocs/langs/fr_FR/main.lang
@@ -620,6 +620,7 @@ MonthVeryShort11=N
 MonthVeryShort12=D
 AttachedFiles=Fichiers et documents joints
 JoinMainDoc=Joindre le document principal
+JoinMainDocOrLastGenerated=Joindre le document principal ou le dernier généré s'il n'a pas été trouvé
 DateFormatYYYYMM=YYYY-MM
 DateFormatYYYYMMDD=YYYY-MM-DD
 DateFormatYYYYMMDDHHMM=YYYY-MM-DD HH:SS