Use belongs to.

Author: binaryk

src/Models/MailTemplate.php

@@ -38,7 +38,9 @@ class MailTemplate extends Model implements MailTemplateable
 
     public function placeholders()
     {
-        return $this->hasMany(MailTemplatePlaceholder::class, 'mail_template_id');
+        return $this->hasMany(
+            config('mailator.templates.placeholder_model') ?? MailTemplatePlaceholder::class, 'mail_template_id'
+        );
     }
 
     public function htmlWithInlinedCss(): string

src/Models/MailTemplatePlaceholder.php

@@ -22,6 +22,8 @@ class MailTemplatePlaceholder extends Model
 
     public function mailTemplate()
     {
-        return $this->belongsTo(MailTemplate::class, 'mail_template_id');
+        return $this->belongsTo(
+            config('mailator.templates.template_model') ?? MailTemplate::class, 'mail_template_id'
+        );
     }
 }