diff --git a/config/tags.go b/config/tags.go
index 080a846..6b152f9 100644
--- a/config/tags.go
+++ b/config/tags.go
@@ -94,9 +94,9 @@ func parseTagsDisable(s string) error {
 		return nil
 	}
 
-	parts := strings.Split(strings.ToLower(s), ",")
+	parts := strings.SplitSeq(strings.ToLower(s), ",")
 
-	for _, p := range parts {
+	for p := range parts {
 		switch strings.TrimSpace(p) {
 		case "x-tags", "xtags":
 			TagsDisableXTags = true
diff --git a/config/validators.go b/config/validators.go
index fe01328..c9b1d8a 100644
--- a/config/validators.go
+++ b/config/validators.go
@@ -26,8 +26,8 @@ func parseMaxAge() error {
 		return fmt.Errorf("max-age must be either <int>h for hours or <int>d for days: %s", MaxAge)
 	}
 
-	if strings.HasSuffix(MaxAge, "h") {
-		hours, err := strconv.Atoi(strings.TrimSuffix(MaxAge, "h"))
+	if before, ok := strings.CutSuffix(MaxAge, "h"); ok {
+		hours, err := strconv.Atoi(before)
 		if err != nil {
 			return err
 		}
@@ -221,8 +221,8 @@ func validateForwardConfig() error {
 	}
 
 	to := []string{}
-	addresses := strings.Split(SMTPForwardConfig.To, ",")
-	for _, a := range addresses {
+	addresses := strings.SplitSeq(SMTPForwardConfig.To, ",")
+	for a := range addresses {
 		a = strings.TrimSpace(a)
 		m, err := mail.ParseAddress(a)
 		if err != nil {
@@ -263,8 +263,8 @@ func parseChaosTriggers() error {
 
 	re := regexp.MustCompile(`^([a-zA-Z0-0]+):(\d\d\d):(\d+(\.\d)?)$`)
 
-	parts := strings.Split(ChaosTriggers, ",")
-	for _, p := range parts {
+	parts := strings.SplitSeq(ChaosTriggers, ",")
+	for p := range parts {
 		p = strings.TrimSpace(p)
 		if !re.MatchString(p) {
 			return fmt.Errorf("invalid argument: %s", p)
diff --git a/internal/htmlcheck/caniemail.go b/internal/htmlcheck/caniemail.go
index 8b33acd..4d4c947 100644
--- a/internal/htmlcheck/caniemail.go
+++ b/internal/htmlcheck/caniemail.go
@@ -42,19 +42,19 @@ type CanIEmail struct {
 
 // JSONResult struct for CanIEmail Data
 type JSONResult struct {
-	Slug           string                 `json:"slug"`
-	Title          string                 `json:"title"`
-	Description    string                 `json:"description"`
-	URL            string                 `json:"url"`
-	Category       string                 `json:"category"`
-	Tags           []string               `json:"tags"`
-	Keywords       string                 `json:"keywords"`
-	LastTestDate   string                 `json:"last_test_date"`
-	TestURL        string                 `json:"test_url"`
-	TestResultsURL string                 `json:"test_results_url"`
-	Stats          map[string]interface{} `json:"stats"`
-	Notes          string                 `json:"notes"`
-	NotesByNumber  map[string]string      `json:"notes_by_num"`
+	Slug           string            `json:"slug"`
+	Title          string            `json:"title"`
+	Description    string            `json:"description"`
+	URL            string            `json:"url"`
+	Category       string            `json:"category"`
+	Tags           []string          `json:"tags"`
+	Keywords       string            `json:"keywords"`
+	LastTestDate   string            `json:"last_test_date"`
+	TestURL        string            `json:"test_url"`
+	TestResultsURL string            `json:"test_results_url"`
+	Stats          map[string]any    `json:"stats"`
+	Notes          string            `json:"notes"`
+	NotesByNumber  map[string]string `json:"notes_by_num"`
 }
 
 // Load the JSON data
diff --git a/internal/htmlcheck/inline_test.go b/internal/htmlcheck/inline_test.go
index 02fe574..8843f19 100644
--- a/internal/htmlcheck/inline_test.go
+++ b/internal/htmlcheck/inline_test.go
@@ -72,7 +72,7 @@ func TestInlineStyleDetection(t *testing.T) {
 	}
 }
 
-func assertEqual(t *testing.T, a interface{}, b interface{}, message string) {
+func assertEqual(t *testing.T, a any, b any, message string) {
 	if a == b {
 		return
 	}
diff --git a/internal/htmlcheck/main.go b/internal/htmlcheck/main.go
index aad4a95..87611fd 100644
--- a/internal/htmlcheck/main.go
+++ b/internal/htmlcheck/main.go
@@ -141,11 +141,11 @@ func (c CanIEmail) getTest(k string) (Warning, error) {
 			continue
 		}
 
-		for platform, clients := range stats.(map[string]interface{}) {
+		for platform, clients := range stats.(map[string]any) {
 			if len(LimitPlatforms) != 0 && !tools.InArray(platform, LimitPlatforms) {
 				continue
 			}
-			for version, support := range clients.(map[string]interface{}) {
+			for version, support := range clients.(map[string]any) {
 				s := Result{}
 				s.Name = fmt.Sprintf("%s %s (%s)", c.NiceNames.Family[family], c.NiceNames.Platform[platform], version)
 				s.Family = family
diff --git a/internal/htmlcheck/platforms.go b/internal/htmlcheck/platforms.go
index 42c0c79..e72eaea 100644
--- a/internal/htmlcheck/platforms.go
+++ b/internal/htmlcheck/platforms.go
@@ -1,7 +1,7 @@
 package htmlcheck
 
 import (
-	"sort"
+	"slices"
 
 	"github.com/axllent/mailpit/internal/tools"
 )
@@ -18,7 +18,7 @@ func Platforms() (map[string][]string, error) {
 	for _, t := range cie.Data {
 		for family, stats := range t.Stats {
 			niceFamily := cie.NiceNames.Family[family]
-			for platform := range stats.(map[string]interface{}) {
+			for platform := range stats.(map[string]any) {
 				c, found := data[platform]
 				if !found {
 					data[platform] = []string{}
@@ -32,9 +32,7 @@ func Platforms() (map[string][]string, error) {
 	}
 
 	for group, clients := range data {
-		sort.Slice(clients, func(i, j int) bool {
-			return clients[i] < clients[j]
-		})
+		slices.Sort(clients)
 		data[group] = clients
 	}
 
diff --git a/internal/logger/logger.go b/internal/logger/logger.go
index 88b31ec..0132be2 100644
--- a/internal/logger/logger.go
+++ b/internal/logger/logger.go
@@ -61,7 +61,7 @@ func Log() *logrus.Logger {
 }
 
 // PrettyPrint for debugging
-func PrettyPrint(i interface{}) {
+func PrettyPrint(i any) {
 	s, _ := json.MarshalIndent(i, "", "\t")
 	fmt.Println(string(s))
 }
diff --git a/internal/pop3/pop3_test.go b/internal/pop3/pop3_test.go
index cbaad5a..d6eff55 100644
--- a/internal/pop3/pop3_test.go
+++ b/internal/pop3/pop3_test.go
@@ -362,11 +362,11 @@ func randRange(min, max int) int {
 }
 
 func insertEmailData(t *testing.T) {
-	for i := 0; i < 50; i++ {
+	for i := range 50 {
 		msg := enmime.Builder().
 			From(fmt.Sprintf("From %d", i), fmt.Sprintf("from-%d@example.com", i)).
 			Subject(fmt.Sprintf("Subject line %d end", i)).
-			Text([]byte(fmt.Sprintf("This is the email body %d <jdsauk;dwqmdqw;>.", i))).
+			Text(fmt.Appendf(nil, "This is the email body %d <jdsauk;dwqmdqw;>.", i)).
 			To(fmt.Sprintf("To %d", i), fmt.Sprintf("to-%d@example.com", i))
 
 		env, err := msg.Build()
@@ -397,7 +397,7 @@ func insertEmailData(t *testing.T) {
 	}
 }
 
-func assertEqual(t *testing.T, a interface{}, b interface{}, message string) {
+func assertEqual(t *testing.T, a any, b any, message string) {
 	if a == b {
 		return
 	}
diff --git a/internal/pop3client/client.go b/internal/pop3client/client.go
index a048cf1..31feae6 100644
--- a/internal/pop3client/client.go
+++ b/internal/pop3client/client.go
@@ -138,7 +138,7 @@ func (c *Conn) Send(b string) error {
 // in case of single line responses, or a help message followed by multiple lines of actual response
 // data in case of multiline responses.
 // See https://www.shellhacks.com/retrieve-email-pop3-server-command-line/ for examples.
-func (c *Conn) Cmd(cmd string, isMulti bool, args ...interface{}) (*bytes.Buffer, error) {
+func (c *Conn) Cmd(cmd string, isMulti bool, args ...any) (*bytes.Buffer, error) {
 	var cmdLine string
 
 	// Repeat a %v to format each arg.
@@ -441,12 +441,12 @@ func parseResp(b []byte) ([]byte, error) {
 
 	if bytes.Equal(b, respOK) {
 		return nil, nil
-	} else if bytes.HasPrefix(b, respOKInfo) {
-		return bytes.TrimPrefix(b, respOKInfo), nil
+	} else if after, ok := bytes.CutPrefix(b, respOKInfo); ok {
+		return after, nil
 	} else if bytes.Equal(b, respErr) {
 		return nil, errors.New("unknown error (no info specified in response)")
-	} else if bytes.HasPrefix(b, respErrInfo) {
-		return nil, errors.New(string(bytes.TrimPrefix(b, respErrInfo)))
+	} else if after, ok := bytes.CutPrefix(b, respErrInfo); ok {
+		return nil, errors.New(string(after))
 	}
 
 	return nil, fmt.Errorf("unknown response: %s. Neither -ERR, nor +OK", string(b))
diff --git a/internal/smtpd/forward.go b/internal/smtpd/forward.go
index 56baf60..c38a133 100644
--- a/internal/smtpd/forward.go
+++ b/internal/smtpd/forward.go
@@ -108,9 +108,9 @@ func forward(from string, msg []byte) error {
 		return fmt.Errorf("error response to MAIL command: %s", err.Error())
 	}
 
-	to := strings.Split(config.SMTPForwardConfig.To, ",")
+	to := strings.SplitSeq(config.SMTPForwardConfig.To, ",")
 
-	for _, addr := range to {
+	for addr := range to {
 		if err = c.Rcpt(addr); err != nil {
 			logger.Log().Warnf("error response to RCPT command for %s: %s", addr, err.Error())
 			if config.SMTPForwardConfig.ForwardSMTPErrors {
diff --git a/internal/smtpd/smtpd.go b/internal/smtpd/smtpd.go
index 43e19b9..1915f81 100644
--- a/internal/smtpd/smtpd.go
+++ b/internal/smtpd/smtpd.go
@@ -337,7 +337,7 @@ func (srv *Server) Shutdown(ctx context.Context) error {
 	timer := time.NewTimer(100 * time.Millisecond)
 	defer timer.Stop()
 
-	for i := 0; i < 300; i++ {
+	for range 300 {
 		// wait for open sessions to close
 		if atomic.LoadInt32(&srv.openSessions) == 0 {
 			break
@@ -636,8 +636,8 @@ loop:
 		case "XCLIENT":
 			s.xClient = args
 			if s.xClientTrust {
-				xCArgs := strings.Split(args, " ")
-				for _, xCArg := range xCArgs {
+				xCArgs := strings.SplitSeq(args, " ")
+				for xCArg := range xCArgs {
 					xCParse := strings.Split(strings.TrimSpace(xCArg), "=")
 					if strings.ToUpper(xCParse[0]) == "ADDR" && (net.ParseIP(xCParse[1]) != nil) {
 						s.xClientADDR = xCParse[1]
@@ -786,7 +786,7 @@ loop:
 }
 
 // Wrapper function for writing a complete line to the socket.
-func (s *session) writef(format string, args ...interface{}) {
+func (s *session) writef(format string, args ...any) {
 	if s.srv.Timeout > 0 {
 		_ = s.conn.SetWriteDeadline(time.Now().Add(s.srv.Timeout))
 	}
@@ -831,9 +831,9 @@ func (s *session) readLine() (string, error) {
 
 // Parse a line read from the socket.
 func (s *session) parseLine(line string) (verb string, args string) {
-	if idx := strings.Index(line, " "); idx != -1 {
-		verb = strings.ToUpper(line[:idx])
-		args = strings.TrimSpace(line[idx+1:])
+	if before, after, ok := strings.Cut(line, " "); ok {
+		verb = strings.ToUpper(before)
+		args = strings.TrimSpace(after)
 	} else {
 		verb = strings.ToUpper(line)
 		args = ""
diff --git a/internal/smtpd/smtpd_test.go b/internal/smtpd/smtpd_test.go
index 45b77f7..98a462c 100644
--- a/internal/smtpd/smtpd_test.go
+++ b/internal/smtpd/smtpd_test.go
@@ -779,8 +779,8 @@ func parseExtensions(t *testing.T, greeting string) map[string]string {
 
 			// Add line as extension.
 			line = strings.TrimSpace(line[4:]) // Strip code prefix and trailing \r\n
-			if idx := strings.Index(line, " "); idx != -1 {
-				extensions[line[:idx]] = line[idx+1:]
+			if before, after, ok := strings.Cut(line, " "); ok {
+				extensions[before] = after
 			} else {
 				extensions[line] = ""
 			}
diff --git a/internal/storage/cron.go b/internal/storage/cron.go
index 7e789c0..c6de0b1 100644
--- a/internal/storage/cron.go
+++ b/internal/storage/cron.go
@@ -128,7 +128,7 @@ func pruneMessages() {
 		return
 	}
 
-	args := make([]interface{}, len(ids))
+	args := make([]any, len(ids))
 	for i, id := range ids {
 		args[i] = id
 	}
diff --git a/internal/storage/functions_test.go b/internal/storage/functions_test.go
index dc98da8..fc126c1 100644
--- a/internal/storage/functions_test.go
+++ b/internal/storage/functions_test.go
@@ -49,7 +49,7 @@ func setup(tenantID string) {
 	}
 }
 
-func assertEqual(t *testing.T, a interface{}, b interface{}, message string) {
+func assertEqual(t *testing.T, a any, b any, message string) {
 	if a == b {
 		return
 	}
diff --git a/internal/storage/messages.go b/internal/storage/messages.go
index 1b41961..3a24a71 100644
--- a/internal/storage/messages.go
+++ b/internal/storage/messages.go
@@ -656,7 +656,7 @@ func DeleteMessages(ids []string) error {
 
 	start := time.Now()
 
-	args := make([]interface{}, len(ids))
+	args := make([]any, len(ids))
 	for i, id := range ids {
 		args[i] = id
 	}
@@ -696,7 +696,7 @@ func DeleteMessages(ids []string) error {
 		return err
 	}
 
-	args = make([]interface{}, len(toDelete))
+	args = make([]any, len(toDelete))
 	for i, id := range toDelete {
 		args[i] = id
 	}
diff --git a/internal/storage/messages_test.go b/internal/storage/messages_test.go
index 4f46cbe..0676f6a 100644
--- a/internal/storage/messages_test.go
+++ b/internal/storage/messages_test.go
@@ -16,7 +16,7 @@ func TestTextEmailInserts(t *testing.T) {
 
 	start := time.Now()
 
-	for i := 0; i < testRuns; i++ {
+	for range testRuns {
 		if _, err := Store(&testTextEmail, nil); err != nil {
 			t.Log("error ", err)
 			t.Fail()
@@ -54,7 +54,7 @@ func TestMimeEmailInserts(t *testing.T) {
 
 		start := time.Now()
 
-		for i := 0; i < testRuns; i++ {
+		for range testRuns {
 			if _, err := Store(&testMimeEmail, nil); err != nil {
 				t.Log("error ", err)
 				t.Fail()
diff --git a/internal/storage/search.go b/internal/storage/search.go
index 252b4c9..65a7340 100644
--- a/internal/storage/search.go
+++ b/internal/storage/search.go
@@ -80,10 +80,7 @@ func Search(search, timezone string, start int, beforeTS int64, limit int) ([]Me
 	nrResults = len(allResults)
 
 	if nrResults > start {
-		end := nrResults
-		if nrResults >= start+limit {
-			end = start + limit
-		}
+		end := min(nrResults, start+limit)
 
 		results = allResults[start:end]
 	}
@@ -196,7 +193,7 @@ func DeleteSearch(search, timezone string) error {
 		defer func() { _ = tx.Rollback() }()
 
 		for _, ids := range chunks {
-			delIDs := make([]interface{}, len(ids))
+			delIDs := make([]any, len(ids))
 			for i, id := range ids {
 				delIDs[i] = id
 			}
diff --git a/internal/storage/search_test.go b/internal/storage/search_test.go
index f139ed5..848581d 100644
--- a/internal/storage/search_test.go
+++ b/internal/storage/search_test.go
@@ -22,13 +22,13 @@ func TestSearch(t *testing.T) {
 			t.Logf("Testing search (tenant %s)", tenantID)
 		}
 
-		for i := 0; i < testRuns; i++ {
+		for i := range testRuns {
 			msg := enmime.Builder().
 				From(fmt.Sprintf("From %d", i), fmt.Sprintf("from-%d@example.com", i)).
 				CC(fmt.Sprintf("CC %d", i), fmt.Sprintf("cc-%d@example.com", i)).
 				CC(fmt.Sprintf("CC2 %d", i), fmt.Sprintf("cc2-%d@example.com", i)).
 				Subject(fmt.Sprintf("Subject line %d end", i)).
-				Text([]byte(fmt.Sprintf("This is the email body %d <jdsauk;dwqmdqw;>.", i))).
+				Text(fmt.Appendf(nil, "This is the email body %d <jdsauk;dwqmdqw;>.", i)).
 				To(fmt.Sprintf("To %d", i), fmt.Sprintf("to-%d@example.com", i)).
 				To(fmt.Sprintf("To2 %d", i), fmt.Sprintf("to2-%d@example.com", i)).
 				ReplyTo(fmt.Sprintf("Reply To %d", i), fmt.Sprintf("reply-to-%d@example.com", i))
@@ -116,7 +116,7 @@ func TestSearchDelete100(t *testing.T) {
 			t.Logf("Testing search delete of 100 messages (tenant %s)", tenantID)
 		}
 
-		for i := 0; i < 100; i++ {
+		for range 100 {
 			if _, err := Store(&testTextEmail, nil); err != nil {
 				t.Log("error ", err)
 				t.Fail()
@@ -157,7 +157,7 @@ func TestSearchDelete1100(t *testing.T) {
 	defer Close()
 
 	t.Log("Testing search delete of 1100 messages")
-	for i := 0; i < 1100; i++ {
+	for range 1100 {
 		if _, err := Store(&testTextEmail, nil); err != nil {
 			t.Log("error ", err)
 			t.Fail()
diff --git a/internal/storage/tags_test.go b/internal/storage/tags_test.go
index c12cc1b..ba68ed3 100644
--- a/internal/storage/tags_test.go
+++ b/internal/storage/tags_test.go
@@ -3,6 +3,7 @@ package storage
 import (
 	"context"
 	"fmt"
+	"slices"
 	"strings"
 	"testing"
 
@@ -25,7 +26,7 @@ func TestTags(t *testing.T) {
 
 		ids := []string{}
 
-		for i := 0; i < 10; i++ {
+		for range 10 {
 			id, err := Store(&testMimeEmail, nil)
 			if err != nil {
 				t.Log("error ", err)
@@ -34,14 +35,14 @@ func TestTags(t *testing.T) {
 			ids = append(ids, id)
 		}
 
-		for i := 0; i < 10; i++ {
+		for i := range 10 {
 			if _, err := SetMessageTags(ids[i], []string{fmt.Sprintf("Tag-%d", i)}); err != nil {
 				t.Log("error ", err)
 				t.Fail()
 			}
 		}
 
-		for i := 0; i < 10; i++ {
+		for i := range 10 {
 			message, err := GetMessage(ids[i])
 			if err != nil {
 				t.Log("error ", err)
@@ -65,7 +66,7 @@ func TestTags(t *testing.T) {
 			t.Fail()
 		}
 		newTags := []string{}
-		for i := 0; i < 20; i++ {
+		for i := range 20 {
 			// pad number with 0 to ensure they are returned alphabetically
 			newTags = append(newTags, fmt.Sprintf("AnotherTag %02d", i))
 		}
@@ -159,13 +160,7 @@ func TestUsernameAutoTagging(t *testing.T) {
 		if err != nil {
 			t.Fatalf("GetMessage failed: %v", err)
 		}
-		found := false
-		for _, tag := range msg.Tags {
-			if tag == username {
-				found = true
-				break
-			}
-		}
+		found := slices.Contains(msg.Tags, username)
 		if !found {
 			t.Errorf("Expected username '%s' in tags, got %v", username, msg.Tags)
 		}
diff --git a/server/server_test.go b/server/server_test.go
index 0ff9934..5d3b4e0 100644
--- a/server/server_test.go
+++ b/server/server_test.go
@@ -28,7 +28,7 @@ var (
 	}
 
 	// Shared test message structure for consistency
-	testSendMessage = map[string]interface{}{
+	testSendMessage = map[string]any{
 		"From": map[string]string{
 			"Email": "test@example.com",
 		},
@@ -545,11 +545,11 @@ func assertSearchEqual(t *testing.T, uri, query string, count int) {
 }
 
 func insertEmailData(t *testing.T) {
-	for i := 0; i < 100; i++ {
+	for i := range 100 {
 		msg := enmime.Builder().
 			From(fmt.Sprintf("From %d", i), fmt.Sprintf("from-%d@example.com", i)).
 			Subject(fmt.Sprintf("Subject line %d end", i)).
-			Text([]byte(fmt.Sprintf("This is the email body %d <jdsauk;dwqmdqw;>.", i))).
+			Text(fmt.Appendf(nil, "This is the email body %d <jdsauk;dwqmdqw;>.", i)).
 			To(fmt.Sprintf("To %d", i), fmt.Sprintf("to-%d@example.com", i))
 
 		env, err := msg.Build()
@@ -754,7 +754,7 @@ func clientGetWithAuth(url, username, password string) ([]byte, error) {
 	return data, err
 }
 
-func assertEqual(t *testing.T, a interface{}, b interface{}, message string) {
+func assertEqual(t *testing.T, a any, b any, message string) {
 	if a == b {
 		return
 	}
diff --git a/server/websockets/client.go b/server/websockets/client.go
index c56ecd1..43017bf 100644
--- a/server/websockets/client.go
+++ b/server/websockets/client.go
@@ -98,7 +98,7 @@ func (c *Client) writePump() {
 
 			// Add queued chat messages to the current websocket message.
 			n := len(c.send)
-			for i := 0; i < n; i++ {
+			for range n {
 				_, _ = w.Write(newline)
 				_, _ = w.Write(<-c.send)
 			}
diff --git a/server/websockets/hub.go b/server/websockets/hub.go
index e50a9f0..2db98e2 100644
--- a/server/websockets/hub.go
+++ b/server/websockets/hub.go
@@ -27,7 +27,7 @@ type Hub struct {
 // WebsocketNotification struct for responses
 type WebsocketNotification struct {
 	Type string
-	Data interface{}
+	Data any
 }
 
 // NewHub returns a new hub configuration
@@ -69,7 +69,7 @@ func (h *Hub) Run() {
 }
 
 // Broadcast will spawn a broadcast message to all connected clients
-func Broadcast(t string, msg interface{}) {
+func Broadcast(t string, msg any) {
 	if MessageHub == nil || len(MessageHub.Clients) == 0 {
 		return
 	}