diff --git a/README.md b/README.md
index e9a99cb..7e201cc 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,7 @@ so you can use it to send emails from your apps and scripts as well.
 
 - [x] SMTP client
 - [x] SMTP server (you can use Postmoogle as general purpose SMTP server to send emails from your scripts or apps)
+- [x] SMTP Relaying (postmoogle can send emails via relay host), global and per-mailbox
 - [x] Send a message to matrix room with special format to send a new email, even to multiple email addresses at once
 - [x] Reply to matrix thread sends reply into email thread
 - [x] Email signatures
@@ -76,10 +77,10 @@ env vars
 * **POSTMOOGLE_MAILBOXES_ACTIVATION** - activation flow for new mailboxes, [docs/mailboxes.md](docs/mailboxes.md)
 * **POSTMOOGLE_MAXSIZE** - max email size (including attachments) in megabytes
 * **POSTMOOGLE_ADMINS** - a space-separated list of admin users. See `POSTMOOGLE_USERS` for syntax examples
-* **POSTMOOGLE_RELAY_HOST** - SMTP hostname of relay host (e.g. Sendgrid)
-* **POSTMOOGLE_RELAY_PORT** - SMTP port of relay host
-* **POSTMOOGLE_RELAY_USERNAME** - Username of relay host
-* **POSTMOOGLE_RELAY_PASSWORD** - Password of relay host
+* **POSTMOOGLE_RELAY_HOST** - (global) SMTP hostname of relay host (e.g. Sendgrid)
+* **POSTMOOGLE_RELAY_PORT** - (global) SMTP port of relay host
+* **POSTMOOGLE_RELAY_USERNAME** - (global) Username of relay host
+* **POSTMOOGLE_RELAY_PASSWORD** - (global) Password of relay host
 
 You can find default values in [config/defaults.go](config/defaults.go)
 
@@ -118,7 +119,7 @@ If you want to change them - check available options in the help message (`!pm h
 * **`!pm domain`** - Get or set default domain of the room
 * **`!pm owner`** - Get or set owner of the room
 * **`!pm password`** - Get or set SMTP password of the room's mailbox
-
+* **`!pm relay`** - Get or set SMTP relay of that mailbox. Format: `smtp://user:password@host:port`, e.g. `smtp://54b7bfb9-b95f-44b8-9879-9b560baf4e3a:8528a3a9-bea8-4583-9912-d4357ba565eb@example.com:587`
 ---
 
 #### mailbox options
diff --git a/bot/bot.go b/bot/bot.go
index 23bb86c..ca633d3 100644
--- a/bot/bot.go
+++ b/bot/bot.go
@@ -3,6 +3,7 @@ package bot
 import (
 	"context"
 	"fmt"
+	"net/url"
 	"regexp"
 	"sync"
 
@@ -36,7 +37,7 @@ type Bot struct {
 	commands                commandList
 	rooms                   sync.Map
 	proxies                 []string
-	sendmail                func(string, string, string) error
+	sendmail                func(string, string, string, *url.URL) error
 	psdc                    *psd.Client
 	cfg                     *config.Manager
 	log                     *zerolog.Logger
diff --git a/bot/command.go b/bot/command.go
index 01cc8fe..a37404b 100644
--- a/bot/command.go
+++ b/bot/command.go
@@ -103,6 +103,12 @@ func (b *Bot) initCommands() commandList {
 			description: "Get or set SMTP password of the room's mailbox",
 			allowed:     b.allowOwner,
 		},
+		{
+			key:         config.RoomRelay,
+			description: "Configure SMTP Relay for that mailbox, format: `smtp://user:pass@host:port`",
+			sanitizer:   utils.SanitizeURL,
+			allowed:     b.allowOwner,
+		},
 		{allowed: b.allowOwner, description: "mailbox options"}, // delimiter
 		{
 			key:         config.RoomAutoreply,
@@ -630,7 +636,7 @@ func (b *Bot) runSendCommand(ctx context.Context, cfg config.Room, tos []string,
 			b.lp.SendNotice(ctx, evt.RoomID, "email body is empty", linkpearl.RelatesTo(evt.ID, cfg.NoThreads()))
 			return
 		}
-		queued, err := b.Sendmail(ctx, evt.ID, from, to, data)
+		queued, err := b.Sendmail(ctx, evt.ID, from, to, data, cfg.Relay())
 		if queued {
 			b.log.Warn().Err(err).Msg("email has been queued")
 			b.saveSentMetadata(ctx, queued, evt.ID, to, eml, cfg)
diff --git a/bot/command_owner.go b/bot/command_owner.go
index a175d58..57fe0d2 100644
--- a/bot/command_owner.go
+++ b/bot/command_owner.go
@@ -51,6 +51,8 @@ func (b *Bot) handleOption(ctx context.Context, cmd []string) {
 		b.setMailbox(ctx, cmd[1])
 	case config.RoomPassword:
 		b.setPassword(ctx)
+	case config.RoomRelay:
+		b.setRelay(ctx)
 	default:
 		b.setOption(ctx, cmd[0], cmd[1])
 	}
@@ -152,6 +154,25 @@ func (b *Bot) setPassword(ctx context.Context) {
 	b.lp.SendNotice(ctx, evt.RoomID, "SMTP password has been set", linkpearl.RelatesTo(evt.ID, cfg.NoThreads()))
 }
 
+func (b *Bot) setRelay(ctx context.Context) {
+	evt := eventFromContext(ctx)
+	cfg, err := b.cfg.GetRoom(ctx, evt.RoomID)
+	if err != nil {
+		b.Error(ctx, "failed to retrieve settings: %v", err)
+		return
+	}
+
+	value := b.parseCommand(evt.Content.AsMessage().Body, false)[1] // get original value, without forced lower case
+	cfg.Set(config.RoomRelay, value)
+	err = b.cfg.SetRoom(ctx, evt.RoomID, cfg)
+	if err != nil {
+		b.Error(ctx, "cannot update settings: %v", err)
+		return
+	}
+
+	b.lp.SendNotice(ctx, evt.RoomID, "Relay config has been set", linkpearl.RelatesTo(evt.ID, cfg.NoThreads()))
+}
+
 func (b *Bot) setOption(ctx context.Context, name, value string) {
 	cmd := b.commands.get(name)
 	if cmd != nil && cmd.sanitizer != nil {
diff --git a/bot/config/room.go b/bot/config/room.go
index 104bc9e..cc06bbf 100644
--- a/bot/config/room.go
+++ b/bot/config/room.go
@@ -1,8 +1,11 @@
 package config
 
 import (
+	"fmt"
+	"net/url"
 	"strings"
 
+	"gitlab.com/etke.cc/go/healthchecks/v2"
 	"gitlab.com/etke.cc/postmoogle/email"
 	"gitlab.com/etke.cc/postmoogle/utils"
 )
@@ -21,6 +24,7 @@ const (
 	RoomPassword  = "password"
 	RoomSignature = "signature"
 	RoomAutoreply = "autoreply"
+	RoomRelay     = "relay"
 
 	RoomThreadify   = "threadify"
 	RoomStripify    = "stripify"
@@ -69,6 +73,20 @@ func (s Room) Active() bool {
 	return utils.Bool(s.Get(RoomActive))
 }
 
+// Relay returns the SMTP Relay configuration in a manner of URL: smtp://user:pass@host:port
+func (s Room) Relay() *url.URL {
+	relay := s.Get(RoomRelay)
+	if relay == "" {
+		return nil
+	}
+	u, err := url.Parse(relay)
+	if err != nil {
+		healthchecks.Global().Fail(strings.NewReader(fmt.Sprintf("cannot parse relay URL %q: %v", relay, err)))
+		return nil
+	}
+	return u
+}
+
 func (s Room) Password() string {
 	return s.Get(RoomPassword)
 }
diff --git a/bot/email.go b/bot/email.go
index cf81146..c2c03bf 100644
--- a/bot/email.go
+++ b/bot/email.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net/url"
 	"strings"
 	"time"
 
@@ -36,7 +37,7 @@ const (
 var ErrNoRoom = errors.New("room not found")
 
 // SetSendmail sets mail sending func to the bot
-func (b *Bot) SetSendmail(sendmail func(string, string, string) error) {
+func (b *Bot) SetSendmail(sendmail func(string, string, string, *url.URL) error) {
 	b.sendmail = sendmail
 	b.q.SetSendmail(sendmail)
 }
@@ -60,14 +61,14 @@ func (b *Bot) shouldQueue(msg string) bool {
 
 // Sendmail tries to send email immediately, but if it gets 4xx error (greylisting),
 // the email will be added to the queue and retried several times after that
-func (b *Bot) Sendmail(ctx context.Context, eventID id.EventID, from, to, data string) (bool, error) {
+func (b *Bot) Sendmail(ctx context.Context, eventID id.EventID, from, to, data string, relayOverride *url.URL) (bool, error) {
 	log := b.log.With().Str("from", from).Str("to", to).Str("eventID", eventID.String()).Logger()
 	log.Info().Msg("attempting to deliver email")
-	err := b.sendmail(from, to, data)
+	err := b.sendmail(from, to, data, relayOverride)
 	if err != nil {
 		if b.shouldQueue(err.Error()) {
 			log.Info().Err(err).Msg("email has been added to the queue")
-			return true, b.q.Add(ctx, eventID.String(), from, to, data)
+			return true, b.q.Add(ctx, eventID.String(), from, to, data, relayOverride)
 		}
 		log.Warn().Err(err).Msg("email delivery failed")
 		return false, err
@@ -82,6 +83,16 @@ func (b *Bot) GetDKIMprivkey(ctx context.Context) string {
 	return b.cfg.GetBot(ctx).DKIMPrivateKey()
 }
 
+// GetRelayConfig returns relay config for specific room (mailbox) if set
+func (b *Bot) GetRelayConfig(ctx context.Context, roomID id.RoomID) *url.URL {
+	cfg, err := b.cfg.GetRoom(ctx, roomID)
+	if err != nil {
+		b.log.Error().Err(err).Str("room_id", roomID.String()).Msg("cannot get room config")
+		return nil
+	}
+	return cfg.Relay()
+}
+
 func (b *Bot) getMapping(mailbox string) (id.RoomID, bool) {
 	v, ok := b.rooms.Load(mailbox)
 	if !ok {
@@ -277,7 +288,7 @@ func (b *Bot) sendAutoreply(ctx context.Context, roomID id.RoomID, threadID id.E
 	ctx = newContext(ctx, threadEvt)
 	recipients := meta.Recipients
 	for _, to := range recipients {
-		queued, err = b.Sendmail(ctx, evt.ID, meta.From, to, data)
+		queued, err = b.Sendmail(ctx, evt.ID, meta.From, to, data, cfg.Relay())
 		if queued {
 			b.log.Info().Err(err).Str("from", meta.From).Str("to", to).Msg("email has been queued")
 			b.saveSentMetadata(ctx, queued, meta.ThreadID, to, eml, cfg, "Autoreply has been sent to "+to+" (queued)")
@@ -361,7 +372,7 @@ func (b *Bot) SendEmailReply(ctx context.Context) {
 	var queued bool
 	recipients := meta.Recipients
 	for _, to := range recipients {
-		queued, err = b.Sendmail(ctx, evt.ID, meta.From, to, data)
+		queued, err = b.Sendmail(ctx, evt.ID, meta.From, to, data, cfg.Relay())
 		if queued {
 			b.log.Info().Err(err).Str("from", meta.From).Str("to", to).Msg("email has been queued")
 			b.saveSentMetadata(ctx, queued, meta.ThreadID, to, eml, cfg)
diff --git a/bot/queue/manager.go b/bot/queue/manager.go
index 286acc2..a2004ae 100644
--- a/bot/queue/manager.go
+++ b/bot/queue/manager.go
@@ -2,6 +2,7 @@ package queue
 
 import (
 	"context"
+	"net/url"
 
 	"github.com/rs/zerolog"
 	"gitlab.com/etke.cc/linkpearl"
@@ -22,7 +23,7 @@ type Queue struct {
 	lp       *linkpearl.Linkpearl
 	cfg      *config.Manager
 	log      *zerolog.Logger
-	sendmail func(string, string, string) error
+	sendmail func(string, string, string, *url.URL) error
 }
 
 // New queue
@@ -36,7 +37,7 @@ func New(lp *linkpearl.Linkpearl, cfg *config.Manager, log *zerolog.Logger) *Que
 }
 
 // SetSendmail func
-func (q *Queue) SetSendmail(function func(string, string, string) error) {
+func (q *Queue) SetSendmail(function func(string, string, string, *url.URL) error) {
 	q.sendmail = function
 }
 
diff --git a/bot/queue/queue.go b/bot/queue/queue.go
index 50501ee..37b7118 100644
--- a/bot/queue/queue.go
+++ b/bot/queue/queue.go
@@ -2,14 +2,20 @@ package queue
 
 import (
 	"context"
+	"net/url"
 	"strconv"
 )
 
 // Add to queue
-func (q *Queue) Add(ctx context.Context, id, from, to, data string) error {
+func (q *Queue) Add(ctx context.Context, id, from, to, data string, relayOverride ...*url.URL) error {
 	itemkey := acQueueKey + "." + id
+	relay := ""
+	if len(relayOverride) > 0 {
+		relay = relayOverride[0].String()
+	}
 	item := map[string]string{
 		"attempts": "0",
+		"relay":    relay,
 		"data":     data,
 		"from":     from,
 		"to":       to,
@@ -84,7 +90,12 @@ func (q *Queue) try(ctx context.Context, itemkey string, maxRetries int) bool {
 		return true
 	}
 
-	err = q.sendmail(item["from"], item["to"], item["data"])
+	var relayOverride *url.URL
+	if item["relay"] != "" {
+		relayOverride, _ = url.Parse(item["relay"]) //nolint:errcheck // doesn't matter
+	}
+
+	err = q.sendmail(item["from"], item["to"], item["data"], relayOverride)
 	if err == nil {
 		q.log.Info().Str("id", itemkey).Msg("email from queue was delivered")
 		return true
diff --git a/cmd/cmd.go b/cmd/cmd.go
index 26fc5d8..7d1011e 100644
--- a/cmd/cmd.go
+++ b/cmd/cmd.go
@@ -148,7 +148,7 @@ func initSMTP(cfg *config.Config) {
 		Relay: &smtp.RelayConfig{
 			Host:     cfg.Relay.Host,
 			Port:     cfg.Relay.Port,
-			Usename:  cfg.Relay.Username,
+			Username: cfg.Relay.Username,
 			Password: cfg.Relay.Password,
 		},
 	})
diff --git a/smtp/client.go b/smtp/client.go
index c6667a4..3183556 100644
--- a/smtp/client.go
+++ b/smtp/client.go
@@ -6,13 +6,14 @@ import (
 	"io"
 	"net"
 	"net/smtp"
+	"net/url"
 	"strings"
 
 	"github.com/rs/zerolog"
 )
 
 type MailSender interface {
-	Send(from, to, data string) error
+	Send(from, to, data string, relayOverride *url.URL) error
 }
 
 // SMTP client
@@ -30,16 +31,35 @@ func newClient(cfg *RelayConfig, log *zerolog.Logger) *Client {
 	}
 }
 
+// relayFromURL creates a RelayConfig from a URL
+func relayFromURL(relayURL *url.URL) *RelayConfig {
+	if relayURL == nil {
+		return nil
+	}
+	password, _ := relayURL.User.Password()
+	return &RelayConfig{
+		Host:     relayURL.Hostname(),
+		Port:     relayURL.Port(),
+		Username: relayURL.User.Username(),
+		Password: password,
+	}
+}
+
 // Send email
-func (c Client) Send(from, to, data string) error {
+func (c Client) Send(from, to, data string, relayOverride *url.URL) error {
 	log := c.log.With().Str("from", from).Str("to", to).Logger()
 	log.Debug().Msg("sending email")
 
+	relay := c.config
+	if relayOverrideCfg := relayFromURL(relayOverride); relayOverrideCfg != nil {
+		relay = relayOverrideCfg
+	}
+
 	var conn *smtp.Client
 	var err error
-	if c.config.Host != "" {
+	if relay != nil && relay.Host != "" {
 		log.Debug().Msg("creating relay client...")
-		conn, err = c.createRelayClient(from, to)
+		conn, err = c.createRelayClient(relay, from, to)
 	} else {
 		log.Debug().Msg("trying direct SMTP connection...")
 		conn, err = c.createDirectClient(from, to)
@@ -73,9 +93,9 @@ func (c Client) Send(from, to, data string) error {
 }
 
 // createRelayClientconnects directly to the provided smtp host
-func (c *Client) createRelayClient(from, to string) (*smtp.Client, error) {
+func (c *Client) createRelayClient(config *RelayConfig, from, to string) (*smtp.Client, error) {
 	localname := strings.SplitN(from, "@", 2)[1]
-	target := c.config.Host + ":" + c.config.Port
+	target := config.Host + ":" + config.Port
 	conn, err := smtp.Dial(target)
 	if err != nil {
 		return nil, err
@@ -87,12 +107,12 @@ func (c *Client) createRelayClient(from, to string) (*smtp.Client, error) {
 	}
 
 	if ok, _ := conn.Extension("STARTTLS"); ok {
-		config := &tls.Config{ServerName: c.config.Host} //nolint:gosec // it's smtp, even that is too strict sometimes
-		conn.StartTLS(config)                            //nolint:errcheck // if it doesn't work - we can't do anything anyway
+		tlsConfig := &tls.Config{ServerName: config.Host} //nolint:gosec // it's smtp, even that is too strict sometimes
+		conn.StartTLS(tlsConfig)                          //nolint:errcheck // if it doesn't work - we can't do anything anyway
 	}
 
-	if c.config.Usename != "" {
-		err = conn.Auth(smtp.PlainAuth("", c.config.Usename, c.config.Password, c.config.Host))
+	if config.Username != "" {
+		err = conn.Auth(smtp.PlainAuth("", config.Username, config.Password, config.Host))
 		if err != nil {
 			conn.Close()
 			return nil, err
diff --git a/smtp/manager.go b/smtp/manager.go
index 7fc1c20..64f81e1 100644
--- a/smtp/manager.go
+++ b/smtp/manager.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"crypto/tls"
 	"net"
+	"net/url"
 	"sync"
 	"time"
 
@@ -44,7 +45,7 @@ type TLSConfig struct {
 type RelayConfig struct {
 	Host     string
 	Port     string
-	Usename  string
+	Username string
 	Password string
 }
 
@@ -70,11 +71,12 @@ type matrixbot interface {
 	GetIFOptions(context.Context, id.RoomID) email.IncomingFilteringOptions
 	IncomingEmail(context.Context, *email.Email) error
 	GetDKIMprivkey(context.Context) string
+	GetRelayConfig(context.Context, id.RoomID) *url.URL
 }
 
 // Caller is Sendmail caller
 type Caller interface {
-	SetSendmail(func(string, string, string) error)
+	SetSendmail(func(string, string, string, *url.URL) error)
 }
 
 // NewManager creates new SMTP server manager
diff --git a/smtp/session.go b/smtp/session.go
index 5ced23d..01e05ea 100644
--- a/smtp/session.go
+++ b/smtp/session.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"io"
 	"net"
+	"net/url"
 	"strconv"
 
 	"github.com/emersion/go-msgauth/dkim"
@@ -40,7 +41,7 @@ type session struct {
 	ctx      context.Context //nolint:containedctx // that's session
 	conn     *smtp.Conn
 	domains  []string
-	sendmail func(string, string, string) error
+	sendmail func(string, string, string, *url.URL) error
 
 	dir      string
 	tos      []string
@@ -124,7 +125,7 @@ func (s *session) outgoingData(r io.Reader) error {
 	eml := email.FromEnvelope(s.tos[0], envelope)
 	for _, to := range s.tos {
 		eml.RcptTo = to
-		err := s.sendmail(eml.From, to, eml.Compose(s.privkey))
+		err := s.sendmail(eml.From, to, eml.Compose(s.privkey), s.bot.GetRelayConfig(s.ctx, s.fromRoom))
 		if err != nil {
 			return err
 		}
diff --git a/utils/utils.go b/utils/utils.go
index bef0742..704c6b3 100644
--- a/utils/utils.go
+++ b/utils/utils.go
@@ -2,6 +2,7 @@ package utils
 
 import (
 	"net"
+	"net/url"
 	"sort"
 	"strconv"
 	"strings"
@@ -40,6 +41,15 @@ func SanitizeDomain(domain string) string {
 	return domains[0]
 }
 
+// SanitizeURL checks that input URL is valid
+func SanitizeURL(str string) string {
+	parsed, err := url.Parse(str)
+	if err != nil {
+		return ""
+	}
+	return parsed.String()
+}
+
 // Bool converts string to boolean
 func Bool(str string) bool {
 	str = strings.ToLower(str)