diff --git a/hugolib/config_test.go b/hugolib/config_test.go
index 16d07d1aff3..1f9e7377c0d 100644
--- a/hugolib/config_test.go
+++ b/hugolib/config_test.go
@@ -97,7 +97,7 @@ top = "top"
 
 [mediaTypes]
 [mediaTypes."text/m1"]
-suffix = "m1main"
+suffixes = ["m1main"]
 
 [outputFormats.o1]
 mediaType = "text/m1"
@@ -135,9 +135,9 @@ p3 = "p3 theme"
 
 [mediaTypes]
 [mediaTypes."text/m1"]
-suffix = "m1theme"
+suffixes = ["m1theme"]
 [mediaTypes."text/m2"]
-suffix = "m2theme"
+suffixes = ["m2theme"]
 
 [outputFormats.o1]
 mediaType = "text/m1"
@@ -207,10 +207,14 @@ map[string]interface {}{
 	b.AssertObject(`
 map[string]interface {}{
   "text/m1": map[string]interface {}{
-    "suffix": "m1main",
+    "suffixes": []interface {}{
+      "m1main",
+    },
   },
   "text/m2": map[string]interface {}{
-    "suffix": "m2theme",
+    "suffixes": []interface {}{
+      "m2theme",
+    },
   },
 }`, got["mediatypes"])
 
@@ -221,7 +225,6 @@ map[string]interface {}{
     "mediatype": Type{
       MainType: "text",
       SubType: "m1",
-      OldSuffix: "m1main",
       Delimiter: ".",
       Suffixes: []string{
         "m1main",
@@ -233,7 +236,6 @@ map[string]interface {}{
     "mediatype": Type{
       MainType: "text",
       SubType: "m2",
-      OldSuffix: "m2theme",
       Delimiter: ".",
       Suffixes: []string{
         "m2theme",
diff --git a/hugolib/page_bundler_test.go b/hugolib/page_bundler_test.go
index 236672b6507..cfbec04b7ce 100644
--- a/hugolib/page_bundler_test.go
+++ b/hugolib/page_bundler_test.go
@@ -435,7 +435,7 @@ func newTestBundleSources(t *testing.T) (*hugofs.Fs, *viper.Viper) {
 	cfg.Set("baseURL", "https://example.com")
 	cfg.Set("mediaTypes", map[string]interface{}{
 		"text/bepsays": map[string]interface{}{
-			"suffix": "bep",
+			"suffixes": []string{"bep"},
 		},
 	})
 
diff --git a/hugolib/site_output_test.go b/hugolib/site_output_test.go
index 0677dfbfb03..e9a7e113e97 100644
--- a/hugolib/site_output_test.go
+++ b/hugolib/site_output_test.go
@@ -276,14 +276,12 @@ disableKinds = ["page", "section", "taxonomy", "taxonomyTerm", "sitemap", "robot
 
 [mediaTypes]
 [mediaTypes."text/nodot"]
-suffix = ""
 delimiter = ""
 [mediaTypes."text/defaultdelim"]
-suffix = "defd"
+suffixes = ["defd"]
 [mediaTypes."text/nosuffix"]
-suffix = ""
 [mediaTypes."text/customdelim"]
-suffix = "del"
+suffixes = ["del"]
 delimiter = "_"
 
 [outputs]
@@ -321,7 +319,7 @@ baseName = "customdelimbase"
 	th.assertFileContent("public/_redirects", "a dotless")
 	th.assertFileContent("public/defaultdelimbase.defd", "default delimim")
 	// This looks weird, but the user has chosen this definition.
-	th.assertFileContent("public/nosuffixbase.", "no suffix")
+	th.assertFileContent("public/nosuffixbase", "no suffix")
 	th.assertFileContent("public/customdelimbase_del", "custom delim")
 
 	s := h.Sites[0]
@@ -332,7 +330,7 @@ baseName = "customdelimbase"
 
 	require.Equal(t, "/blog/_redirects", outputs.Get("DOTLESS").RelPermalink())
 	require.Equal(t, "/blog/defaultdelimbase.defd", outputs.Get("DEF").RelPermalink())
-	require.Equal(t, "/blog/nosuffixbase.", outputs.Get("NOS").RelPermalink())
+	require.Equal(t, "/blog/nosuffixbase", outputs.Get("NOS").RelPermalink())
 	require.Equal(t, "/blog/customdelimbase_del", outputs.Get("CUS").RelPermalink())
 
 }
diff --git a/media/mediaType.go b/media/mediaType.go
index 787579956c3..9f5ca89ff0e 100644
--- a/media/mediaType.go
+++ b/media/mediaType.go
@@ -15,11 +15,13 @@ package media
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"sort"
 	"strings"
 
-	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/common/maps"
+
 	"github.com/mitchellh/mapstructure"
 )
 
@@ -37,10 +39,9 @@ type Type struct {
 	MainType string `json:"mainType"` // i.e. text
 	SubType  string `json:"subType"`  // i.e. html
 
-	// Deprecated in Hugo 0.44. To be renamed and unexported.
-	// Was earlier used both to set file suffix and to augment the MIME type.
-	// This had its limitations and issues.
-	OldSuffix string `json:"-" mapstructure:"suffix"`
+	// This is the optional suffix after the "+" in the MIME type,
+	//  e.g. "xml" in "applicatiion/rss+xml".
+	mimeSuffix string
 
 	Delimiter string `json:"delimiter"` // e.g. "."
 
@@ -79,7 +80,7 @@ func fromString(t string) (Type, error) {
 		suffix = subParts[1]
 	}
 
-	return Type{MainType: mainType, SubType: subType, OldSuffix: suffix}, nil
+	return Type{MainType: mainType, SubType: subType, mimeSuffix: suffix}, nil
 }
 
 // Type returns a string representing the main- and sub-type of a media type, e.g. "text/css".
@@ -91,8 +92,8 @@ func (m Type) Type() string {
 	// Examples are
 	// image/svg+xml
 	// text/css
-	if m.OldSuffix != "" {
-		return fmt.Sprintf("%s/%s+%s", m.MainType, m.SubType, m.OldSuffix)
+	if m.mimeSuffix != "" {
+		return fmt.Sprintf("%s/%s+%s", m.MainType, m.SubType, m.mimeSuffix)
 	}
 	return fmt.Sprintf("%s/%s", m.MainType, m.SubType)
 
@@ -130,9 +131,9 @@ var (
 	HTMLType       = Type{MainType: "text", SubType: "html", Suffixes: []string{"html"}, Delimiter: defaultDelimiter}
 	JavascriptType = Type{MainType: "application", SubType: "javascript", Suffixes: []string{"js"}, Delimiter: defaultDelimiter}
 	JSONType       = Type{MainType: "application", SubType: "json", Suffixes: []string{"json"}, Delimiter: defaultDelimiter}
-	RSSType        = Type{MainType: "application", SubType: "rss", OldSuffix: "xml", Suffixes: []string{"xml"}, Delimiter: defaultDelimiter}
+	RSSType        = Type{MainType: "application", SubType: "rss", mimeSuffix: "xml", Suffixes: []string{"xml"}, Delimiter: defaultDelimiter}
 	XMLType        = Type{MainType: "application", SubType: "xml", Suffixes: []string{"xml"}, Delimiter: defaultDelimiter}
-	SVGType        = Type{MainType: "image", SubType: "svg", OldSuffix: "xml", Suffixes: []string{"svg"}, Delimiter: defaultDelimiter}
+	SVGType        = Type{MainType: "image", SubType: "svg", mimeSuffix: "xml", Suffixes: []string{"svg"}, Delimiter: defaultDelimiter}
 	TextType       = Type{MainType: "text", SubType: "plain", Suffixes: []string{"txt"}, Delimiter: defaultDelimiter}
 
 	OctetType = Type{MainType: "application", SubType: "octet-stream"}
@@ -182,6 +183,17 @@ func (t Types) GetByType(tp string) (Type, bool) {
 	return Type{}, false
 }
 
+// BySuffix will return all media types matching a suffix.
+func (t Types) BySuffix(suffix string) []Type {
+	var types []Type
+	for _, tt := range t {
+		if match := tt.matchSuffix(suffix); match != "" {
+			types = append(types, tt)
+		}
+	}
+	return types
+}
+
 // GetFirstBySuffix will return the first media type matching the given suffix.
 func (t Types) GetFirstBySuffix(suffix string) (Type, bool) {
 	for _, tt := range t {
@@ -214,9 +226,6 @@ func (t Types) GetBySuffix(suffix string) (tp Type, found bool) {
 }
 
 func (t Type) matchSuffix(suffix string) string {
-	if strings.EqualFold(suffix, t.OldSuffix) {
-		return t.OldSuffix
-	}
 	for _, s := range t.Suffixes {
 		if strings.EqualFold(suffix, s) {
 			return s
@@ -246,9 +255,8 @@ func (t Types) GetByMainSubType(mainType, subType string) (tp Type, found bool)
 	return
 }
 
-func suffixIsDeprecated() {
-	helpers.Deprecated("MediaType", "Suffix in config.toml", `
-Before Hugo 0.44 this was used both to set a custom file suffix and as way
+func suffixIsRemoved() error {
+	return errors.New(`MediaType.Suffix is removed. Before Hugo 0.44 this was used both to set a custom file suffix and as way
 to augment the mediatype definition (what you see after the "+", e.g. "image/svg+xml").
 
 This had its limitations. For one, it was only possible with one file extension per MIME type.
@@ -272,16 +280,13 @@ To:
 [mediaTypes."my/custom-mediatype"]
 suffixes = ["txt"]
 
-Hugo will still respect values set in "suffix" if no value for "suffixes" is provided, but this will be removed
-in a future release.
-
 Note that you can still get the Media Type's suffix from a template: {{ $mediaType.Suffix }}. But this will now map to the MIME type filename.
-`, false)
+`)
 }
 
 // DecodeTypes takes a list of media type configurations and merges those,
 // in the order given, with the Hugo defaults as the last resort.
-func DecodeTypes(maps ...map[string]interface{}) (Types, error) {
+func DecodeTypes(mms ...map[string]interface{}) (Types, error) {
 	var m Types
 
 	// Maps type string to Type. Type string is the full application/svg+xml.
@@ -293,7 +298,7 @@ func DecodeTypes(maps ...map[string]interface{}) (Types, error) {
 		mmm[dt.Type()] = dt
 	}
 
-	for _, mm := range maps {
+	for _, mm := range mms {
 		for k, v := range mm {
 			var mediaType Type
 
@@ -311,24 +316,17 @@ func DecodeTypes(maps ...map[string]interface{}) (Types, error) {
 			}
 
 			vm := v.(map[string]interface{})
+			maps.ToLower(vm)
 			_, delimiterSet := vm["delimiter"]
 			_, suffixSet := vm["suffix"]
 
 			if suffixSet {
-				suffixIsDeprecated()
+				return Types{}, suffixIsRemoved()
 			}
 
-			// Before Hugo 0.44 we had a non-standard use of the Suffix
-			// attribute, and this is now deprecated (use Suffixes for file suffixes).
-			// But we need to keep old configurations working for a while.
-			if len(mediaType.Suffixes) == 0 && mediaType.OldSuffix != "" {
-				mediaType.Suffixes = []string{mediaType.OldSuffix}
-			}
 			// The user may set the delimiter as an empty string.
 			if !delimiterSet && len(mediaType.Suffixes) != 0 {
 				mediaType.Delimiter = defaultDelimiter
-			} else if suffixSet && !delimiterSet {
-				mediaType.Delimiter = defaultDelimiter
 			}
 
 			mmm[k] = mediaType
diff --git a/media/mediaType_test.go b/media/mediaType_test.go
index 6385528ee5d..bf356582f40 100644
--- a/media/mediaType_test.go
+++ b/media/mediaType_test.go
@@ -80,11 +80,19 @@ func TestGetByMainSubType(t *testing.T) {
 	assert.False(found)
 }
 
+func TestBySuffix(t *testing.T) {
+	assert := require.New(t)
+	formats := DefaultTypes.BySuffix("xml")
+	assert.Equal(2, len(formats))
+	assert.Equal("rss", formats[0].SubType)
+	assert.Equal("xml", formats[1].SubType)
+}
+
 func TestGetFirstBySuffix(t *testing.T) {
 	assert := require.New(t)
 	f, found := DefaultTypes.GetFirstBySuffix("xml")
 	assert.True(found)
-	assert.Equal(Type{MainType: "application", SubType: "rss", OldSuffix: "xml", Delimiter: ".", Suffixes: []string{"xml"}, fileSuffix: "xml"}, f)
+	assert.Equal(Type{MainType: "application", SubType: "rss", mimeSuffix: "xml", Delimiter: ".", Suffixes: []string{"xml"}, fileSuffix: "xml"}, f)
 }
 
 func TestFromTypeString(t *testing.T) {
@@ -94,18 +102,18 @@ func TestFromTypeString(t *testing.T) {
 
 	f, err = fromString("application/custom")
 	require.NoError(t, err)
-	require.Equal(t, Type{MainType: "application", SubType: "custom", OldSuffix: "", fileSuffix: ""}, f)
+	require.Equal(t, Type{MainType: "application", SubType: "custom", mimeSuffix: "", fileSuffix: ""}, f)
 
 	f, err = fromString("application/custom+sfx")
 	require.NoError(t, err)
-	require.Equal(t, Type{MainType: "application", SubType: "custom", OldSuffix: "sfx"}, f)
+	require.Equal(t, Type{MainType: "application", SubType: "custom", mimeSuffix: "sfx"}, f)
 
 	_, err = fromString("noslash")
 	require.Error(t, err)
 
 	f, err = fromString("text/xml; charset=utf-8")
 	require.NoError(t, err)
-	require.Equal(t, Type{MainType: "text", SubType: "xml", OldSuffix: ""}, f)
+	require.Equal(t, Type{MainType: "text", SubType: "xml", mimeSuffix: ""}, f)
 	require.Equal(t, "", f.Suffix())
 }
 
@@ -146,28 +154,24 @@ func TestDecodeTypes(t *testing.T) {
 				json, found := tt.GetBySuffix("jasn")
 				require.True(t, found)
 				require.Equal(t, "application/json", json.String(), name)
+				require.Equal(t, ".jasn", json.FullSuffix())
 			}},
 		{
-			"Suffix from key, multiple file suffixes",
+			"MIME suffix in key, multiple file suffixes, custom delimiter",
 			[]map[string]interface{}{
 				{
 					"application/hugo+hg": map[string]interface{}{
-						"Suffixes": []string{"hg1", "hg2"},
+						"suffixes":  []string{"hg1", "hg2"},
+						"Delimiter": "_",
 					}}},
 			false,
 			func(t *testing.T, name string, tt Types) {
 				require.Len(t, tt, len(DefaultTypes)+1)
-				hg, found := tt.GetBySuffix("hg")
-				require.True(t, found)
-				require.Equal(t, "hg", hg.OldSuffix)
-				require.Equal(t, "hg", hg.Suffix())
-				require.Equal(t, ".hg", hg.FullSuffix())
-				require.Equal(t, "application/hugo+hg", hg.String(), name)
-				hg, found = tt.GetBySuffix("hg2")
+				hg, found := tt.GetBySuffix("hg2")
 				require.True(t, found)
-				require.Equal(t, "hg", hg.OldSuffix)
+				require.Equal(t, "hg", hg.mimeSuffix)
 				require.Equal(t, "hg2", hg.Suffix())
-				require.Equal(t, ".hg2", hg.FullSuffix())
+				require.Equal(t, "_hg2", hg.FullSuffix())
 				require.Equal(t, "application/hugo+hg", hg.String(), name)
 
 				hg, found = tt.GetByType("application/hugo+hg")
@@ -178,8 +182,8 @@ func TestDecodeTypes(t *testing.T) {
 			"Add custom media type",
 			[]map[string]interface{}{
 				{
-					"text/hugo": map[string]interface{}{
-						"suffix": "hgo"}}},
+					"text/hugo+hgo": map[string]interface{}{
+						"Suffixes": []string{"hgo2"}}}},
 			false,
 			func(t *testing.T, name string, tt Types) {
 				require.Len(t, tt, len(DefaultTypes)+1)
@@ -188,7 +192,7 @@ func TestDecodeTypes(t *testing.T) {
 				_, found := tt.GetBySuffix("json")
 				require.True(t, found)
 
-				hugo, found := tt.GetBySuffix("hgo")
+				hugo, found := tt.GetBySuffix("hgo2")
 				require.True(t, found)
 				require.Equal(t, "text/hugo+hgo", hugo.String(), name)
 			}},
diff --git a/minifiers/minifiers.go b/minifiers/minifiers.go
index 28058dcd812..073898815fc 100644
--- a/minifiers/minifiers.go
+++ b/minifiers/minifiers.go
@@ -71,60 +71,35 @@ func New(mediaTypes media.Types, outputFormats output.Formats) Client {
 	}
 
 	// We use the Type definition of the media types defined in the site if found.
-	addMinifierFunc(m, mediaTypes, "text/css", "css", css.Minify)
-	addMinifierFunc(m, mediaTypes, "application/javascript", "js", js.Minify)
+	addMinifierFunc(m, mediaTypes, "css", css.Minify)
+	addMinifierFunc(m, mediaTypes, "js", js.Minify)
 	m.AddFuncRegexp(regexp.MustCompile("^(application|text)/(x-)?(java|ecma)script$"), js.Minify)
-	addMinifierFunc(m, mediaTypes, "application/json", "json", json.Minify)
-	addMinifierFunc(m, mediaTypes, "image/svg+xml", "svg", svg.Minify)
-	addMinifierFunc(m, mediaTypes, "application/xml", "xml", xml.Minify)
-	addMinifierFunc(m, mediaTypes, "application/rss", "xml", xml.Minify)
+	addMinifierFunc(m, mediaTypes, "json", json.Minify)
+	addMinifierFunc(m, mediaTypes, "svg", svg.Minify)
+	addMinifierFunc(m, mediaTypes, "xml", xml.Minify)
 
 	// HTML
-	addMinifier(m, mediaTypes, "text/html", "html", htmlMin)
+	addMinifier(m, mediaTypes, "html", htmlMin)
 	for _, of := range outputFormats {
 		if of.IsHTML {
-			addMinifier(m, mediaTypes, of.MediaType.Type(), "html", htmlMin)
+			m.Add(of.MediaType.Type(), htmlMin)
 		}
 	}
-	return Client{m: m}
 
-}
+	return Client{m: m}
 
-func addMinifier(m *minify.M, mt media.Types, typeString, suffix string, min minify.Minifier) {
-	resolvedTypeStr := resolveMediaTypeString(mt, typeString, suffix)
-	m.Add(resolvedTypeStr, min)
-	if resolvedTypeStr != typeString {
-		m.Add(typeString, min)
-	}
 }
 
-func addMinifierFunc(m *minify.M, mt media.Types, typeString, suffix string, fn minify.MinifierFunc) {
-	resolvedTypeStr := resolveMediaTypeString(mt, typeString, suffix)
-	m.AddFunc(resolvedTypeStr, fn)
-	if resolvedTypeStr != typeString {
-		m.AddFunc(typeString, fn)
+func addMinifier(m *minify.M, mt media.Types, suffix string, min minify.Minifier) {
+	types := mt.BySuffix(suffix)
+	for _, t := range types {
+		m.Add(t.Type(), min)
 	}
 }
 
-func resolveMediaTypeString(types media.Types, typeStr, suffix string) string {
-	if m, found := resolveMediaType(types, typeStr, suffix); found {
-		return m.Type()
+func addMinifierFunc(m *minify.M, mt media.Types, suffix string, min minify.MinifierFunc) {
+	types := mt.BySuffix(suffix)
+	for _, t := range types {
+		m.AddFunc(t.Type(), min)
 	}
-	// Fall back to the default.
-	return typeStr
-}
-
-// Make sure we match the matching pattern with what the user have actually defined
-// in his or hers media types configuration.
-func resolveMediaType(types media.Types, typeStr, suffix string) (media.Type, bool) {
-	if m, found := types.GetByType(typeStr); found {
-		return m, true
-	}
-
-	if m, found := types.GetFirstBySuffix(suffix); found {
-		return m, true
-	}
-
-	return media.Type{}, false
-
 }
diff --git a/minifiers/minifiers_test.go b/minifiers/minifiers_test.go
index 6d72dc44e88..a0f0f97b404 100644
--- a/minifiers/minifiers_test.go
+++ b/minifiers/minifiers_test.go
@@ -32,4 +32,10 @@ func TestNew(t *testing.T) {
 
 	assert.NoError(m.Minify(media.CSSType, &b, strings.NewReader("body { color: blue; }")))
 	assert.Equal("body{color:blue}", b.String())
+
+	b.Reset()
+
+	// RSS should be handled as XML
+	assert.NoError(m.Minify(media.RSSType, &b, strings.NewReader("<hello>  Hugo!   </hello>  ")))
+	assert.Equal("<hello>Hugo!</hello>", b.String())
 }
diff --git a/output/outputFormat_test.go b/output/outputFormat_test.go
index 5d0620fa9a6..410fd74ba0e 100644
--- a/output/outputFormat_test.go
+++ b/output/outputFormat_test.go
@@ -93,11 +93,9 @@ func TestGetFormatByExt(t *testing.T) {
 
 func TestGetFormatByFilename(t *testing.T) {
 	noExtNoDelimMediaType := media.TextType
-	noExtNoDelimMediaType.OldSuffix = ""
 	noExtNoDelimMediaType.Delimiter = ""
 
 	noExtMediaType := media.TextType
-	noExtMediaType.OldSuffix = ""
 
 	var (
 		noExtDelimFormat = Format{