diff --git a/app/email_utils.py b/app/email_utils.py
index b8ebd5d9..1d7c85ee 100644
--- a/app/email_utils.py
+++ b/app/email_utils.py
@@ -292,6 +292,10 @@ def send_email(
                 msg, "List-Unsubscribe-Post", "List-Unsubscribe=One-Click"
             )
 
+    # add DKIM
+    email_domain = SUPPORT_EMAIL[SUPPORT_EMAIL.find("@") + 1 :]
+    add_dkim_signature(msg, email_domain)
+
     msg_raw = to_bytes(msg)
 
     transaction = TransactionalEmail.create(email=to_email, commit=True)
diff --git a/email_handler.py b/email_handler.py
index 79532b1f..59e8925a 100644
--- a/email_handler.py
+++ b/email_handler.py
@@ -90,6 +90,7 @@ from app.email.rate_limit import rate_limited
 from app.email.spam import get_spam_score
 from app.email_utils import (
     send_email,
+    add_dkim_signature,
     add_or_replace_header,
     delete_header,
     render,
@@ -103,6 +104,7 @@ from app.email_utils import (
     to_bytes,
     send_email_at_most_times,
     is_valid_alias_address_domain,
+    should_add_dkim_signature,
     add_header,
     get_header_unicode,
     generate_reply_email,
@@ -826,6 +828,8 @@ def forward_email_to_mailbox(
             msg, "List-Unsubscribe-Post", "List-Unsubscribe=One-Click"
         )
 
+    add_dkim_signature(msg, EMAIL_DOMAIN)
+
     LOG.d(
         "Forward mail from %s to %s, mail_options:%s, rcpt_options:%s ",
         contact.website_email,
@@ -1058,6 +1062,9 @@ def handle_reply(envelope, msg: Message, rcpt_to: str) -> (bool, str):
         envelope.rcpt_options,
     )
 
+    if should_add_dkim_signature(alias_domain):
+        add_dkim_signature(msg, alias_domain)
+
     # generate a mail_from for VERP
     verp_mail_from = f"{BOUNCE_PREFIX_FOR_REPLY_PHASE}+{email_log.id}+@{alias_domain}"