diff --git a/lib/mail/renderers/rfc_2822.ex b/lib/mail/renderers/rfc_2822.ex
index 918b49b9..e42739b0 100644
--- a/lib/mail/renderers/rfc_2822.ex
+++ b/lib/mail/renderers/rfc_2822.ex
@@ -156,8 +156,16 @@ defmodule Mail.Renderers.RFC2822 do
     end
   end
 
-  defp render_address({name, email}),
-    do: "#{encode_header_value(~s("#{name}"), :quoted_printable)} <#{validate_address(email)}>"
+  defp render_address({name, email}) do
+    address = validate_address(email)
+    encoded = encode_header_value(name, :quoted_printable)
+
+    if encoded == name do
+      ~s("#{name}" <#{address}>)
+    else
+      "#{encoded} <#{address}>"
+    end
+  end
 
   defp render_address(email), do: validate_address(email)
 
@@ -229,10 +237,24 @@ defmodule Mail.Renderers.RFC2822 do
 
   defp wrap_encoded_words(value) do
     :binary.split(value, "=\r\n", [:global])
-    |> Enum.map(fn chunk -> <<"=?UTF-8?Q?", chunk::binary, "?=">> end)
+    |> Enum.map(fn chunk ->
+      chunk = encode_encoded_word_text(chunk)
+      <<"=?UTF-8?Q?", chunk::binary, "?=">>
+    end)
     |> Enum.join()
   end
 
+  # Per RFC 2047 §5, encoded-words must be recognizable as atoms (RFC 2822 §3.2.4).
+  # Spaces become underscores per RFC 2047 §4.2(2).
+  # All other non-atext characters are QP-encoded.
+  defp encode_encoded_word_text(chunk) do
+    chunk
+    |> String.replace(" ", "_")
+    |> String.replace(~r/[^a-zA-Z0-9!#$%&'*+\-\/=?^_`{|}~]/, fn <<byte>> ->
+      "=" <> Base.encode16(<<byte>>)
+    end)
+  end
+
   @doc """
   Builds a RFC2822 timestamp from an Erlang timestamp
 
diff --git a/test/mail/message_test.exs b/test/mail/message_test.exs
index 3cf9344b..16a90d7c 100644
--- a/test/mail/message_test.exs
+++ b/test/mail/message_test.exs
@@ -219,7 +219,7 @@ defmodule Mail.MessageTest do
       |> Mail.put_subject(subject)
       |> Mail.render()
 
-    encoded_subject = "=?UTF-8?Q?" <> Mail.Encoders.QuotedPrintable.encode(subject) <> "?="
+    encoded_subject = "=?UTF-8?Q?" <> encode_rfc2047(subject) <> "?="
 
     assert String.contains?(txt, encoded_subject)
     assert %Mail.Message{headers: %{"subject" => ^subject}} = Mail.Parsers.RFC2822.parse(txt)
@@ -244,14 +244,46 @@ defmodule Mail.MessageTest do
       |> Mail.put_to(to)
       |> Mail.render()
 
-    encoded_from =
-      ~s(From: =?UTF-8?Q?"#{Mail.Encoders.QuotedPrintable.encode(elem(from, 0))}"?= <#{elem(from, 1)}>)
-
-    encoded_to =
-      ~s(To: =?UTF-8?Q?"#{Mail.Encoders.QuotedPrintable.encode(elem(to, 0))}"?= <#{elem(to, 1)}>)
+    encoded_from = "From: =?UTF-8?Q?#{encode_rfc2047(elem(from, 0))}?= <#{elem(from, 1)}>"
+    encoded_to = "To: =?UTF-8?Q?#{encode_rfc2047(elem(to, 0))}?= <#{elem(to, 1)}>"
 
     assert txt =~ encoded_from
     assert txt =~ encoded_to
+
+    parsed = Mail.Parsers.RFC2822.parse(txt)
+    assert {elem(from, 0), elem(from, 1)} == parsed.headers["from"]
+    assert [{elem(to, 0), elem(to, 1)}] == parsed.headers["to"]
+  end
+
+  test "UTF-8 in addresses round-trips with spaces" do
+    from = {"Mäx Müstermann", "max@example.com"}
+
+    txt =
+      Mail.build()
+      |> Mail.put_from(from)
+      |> Mail.render()
+
+    refute txt =~ ~r/=\?UTF-8\?Q\?[^?]* [^?]*\?=/
+    parsed = Mail.Parsers.RFC2822.parse(txt)
+    assert from == parsed.headers["from"]
+  end
+
+  test "UTF-8 in addresses with comma in name" do
+    from = {"Max, Müstermänn", "max@example.com"}
+    to = {"Other User", "other@example.com"}
+
+    txt =
+      Mail.build()
+      |> Mail.put_from(from)
+      |> Mail.put_to(to)
+      |> Mail.render()
+
+    # Comma must be encoded as =2C, not literal, to avoid being parsed as recipient separator
+    refute txt =~ ~r/=\?UTF-8\?Q\?[^?]*,[^?]*\?=/
+    assert txt =~ "=2C"
+
+    parsed = Mail.Parsers.RFC2822.parse(txt)
+    assert from == parsed.headers["from"]
   end
 
   test "UTF-8 in other header" do
@@ -263,7 +295,7 @@ defmodule Mail.MessageTest do
       |> Mail.render()
 
     encoded_header_value =
-      "=?UTF-8?Q?" <> Mail.Encoders.QuotedPrintable.encode("READMEüä.md") <> "?="
+      "=?UTF-8?Q?" <> encode_rfc2047("READMEüä.md") <> "?="
 
     assert String.contains?(message, encoded_header_value)
 
@@ -282,9 +314,18 @@ defmodule Mail.MessageTest do
       |> Mail.render()
 
     encoded_subject =
-      "=?UTF-8?Q?=C3=BCber alles=0Anew =3F=3D line some =D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C long line?="
+      "=?UTF-8?Q?=C3=BCber_alles=0Anew_=3F=3D_line_some_=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD?==?UTF-8?Q?=D1=8C-=D0=BE=D1=87=D0=B5=D0=BD=D1=8C_long_line?="
 
     assert String.contains?(txt, encoded_subject)
     assert %Mail.Message{headers: %{"subject" => ^subject}} = Mail.Parsers.RFC2822.parse(txt)
   end
+
+  defp encode_rfc2047(string) do
+    string
+    |> Mail.Encoders.QuotedPrintable.encode()
+    |> String.replace(" ", "_")
+    |> String.replace(~r/[^a-zA-Z0-9!#$%&'*+\-\/=?^_`{|}~]/, fn <<byte>> ->
+      "=" <> Base.encode16(<<byte>>)
+    end)
+  end
 end
diff --git a/test/mail/renderers/rfc_2822_test.exs b/test/mail/renderers/rfc_2822_test.exs
index cbacf73a..50a5d818 100644
--- a/test/mail/renderers/rfc_2822_test.exs
+++ b/test/mail/renderers/rfc_2822_test.exs
@@ -52,19 +52,19 @@ defmodule Mail.Renderers.RFC2822Test do
 
     assert Mail.Renderers.RFC2822.render_header("Subject", [
              "Hello World 😀"
-           ]) == "Subject: =?UTF-8?Q?Hello World =F0=9F=98=80?="
+           ]) == "Subject: =?UTF-8?Q?Hello_World_=F0=9F=98=80?="
 
     assert Mail.Renderers.RFC2822.render_header("Subject", [
              "Café résumé"
-           ]) == "Subject: =?UTF-8?Q?Caf=C3=A9 r=C3=A9sum=C3=A9?="
+           ]) == "Subject: =?UTF-8?Q?Caf=C3=A9_r=C3=A9sum=C3=A9?="
 
     assert Mail.Renderers.RFC2822.render_header("Subject", [
              "Hello 世界 World"
-           ]) == "Subject: =?UTF-8?Q?Hello =E4=B8=96=E7=95=8C World?="
+           ]) == "Subject: =?UTF-8?Q?Hello_=E4=B8=96=E7=95=8C_World?="
 
     assert Mail.Renderers.RFC2822.render_header("Subject", [
              "normal subject\r\nReply-To: cleverhacker@example.com"
-           ]) == "Subject: =?UTF-8?Q?normal subject=0D=0AReply-To: cleverhacker@example.com?="
+           ]) == "Subject: =?UTF-8?Q?normal_subject=0D=0AReply-To=3A_cleverhacker=40example=2Ecom?="
 
     assert Mail.Renderers.RFC2822.render_header("Subject", [
              "tabs\t\t and  spaces"
@@ -72,7 +72,7 @@ defmodule Mail.Renderers.RFC2822Test do
 
     assert Mail.Renderers.RFC2822.render_header("Subject", [
              "delete \x7f vertical tab \x0b"
-           ]) == "Subject: =?UTF-8?Q?delete =7F vertical tab =0B?="
+           ]) == "Subject: =?UTF-8?Q?delete_=7F_vertical_tab_=0B?="
   end
 
   test "address headers renders list of recipients" do