diff --git a/docs/MANUAL.md b/docs/MANUAL.md
index 83bfc86a..3a40d1cf 100644
--- a/docs/MANUAL.md
+++ b/docs/MANUAL.md
@@ -621,10 +621,6 @@ In this section, we give an overview of the modes Oragono supports.
 
 These are the modes which can be set on you when you're connected.
 
-### +a - Away
-
-If this mode is set, you're marked as being away. This mode is set with the /AWAY command.
-
 ### +i - Invisible
 
 If this mode is set, you're marked as 'invisible'. This means that your channels won't be shown when users `/WHOIS` you (except for IRC operators, they can see all the channels you're in).
diff --git a/irc/client.go b/irc/client.go
index f88d4a83..c7e36b5c 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -78,8 +78,6 @@ type Client struct {
 	accountName        string // display name of the account: uncasefolded, '*' if not logged in
 	accountRegDate     time.Time
 	accountSettings    AccountSettings
-	away               bool
-	autoAway           bool
 	awayMessage        string
 	brbTimer           BrbTimer
 	channels           ChannelSet
@@ -177,6 +175,9 @@ type Session struct {
 
 	quitMessage string
 
+	awayMessage string
+	awayAt      time.Time
+
 	capabilities caps.Set
 	capState     caps.State
 	capVersion   caps.Version
@@ -486,9 +487,7 @@ func (server *Server) AddAlwaysOnClient(account ClientAccount, channelToStatus m
 	}
 
 	if persistenceEnabled(config.Accounts.Multiclient.AutoAway, client.accountSettings.AutoAway) {
-		client.autoAway = true
-		client.away = true
-		client.awayMessage = client.t("User is currently disconnected")
+		client.setAutoAwayNoMutex(config)
 	}
 }
 
@@ -675,7 +674,7 @@ func (client *Client) run(session *Session) {
 			session.playResume()
 			session.resumeDetails = nil
 			client.brbTimer.Disable()
-			client.SetAway(false, "") // clear BRB message if any
+			session.SetAway("") // clear BRB message if any
 		} else {
 			client.playReattachMessages(session)
 		}
@@ -1459,15 +1458,13 @@ func (client *Client) destroy(session *Session) {
 		client.dirtyBits |= IncludeLastSeen
 	}
 
-	autoAway := false
+	becameAutoAway := false
 	var awayMessage string
-	if alwaysOn && !client.away && remainingSessions == 0 &&
-		persistenceEnabled(config.Accounts.Multiclient.AutoAway, client.accountSettings.AutoAway) {
-		autoAway = true
-		client.autoAway = true
-		client.away = true
-		awayMessage = config.languageManager.Translate(client.languages, `User is currently disconnected`)
-		client.awayMessage = awayMessage
+	if alwaysOn && persistenceEnabled(config.Accounts.Multiclient.AutoAway, client.accountSettings.AutoAway) {
+		wasAway := client.awayMessage != ""
+		client.setAutoAwayNoMutex(config)
+		awayMessage = client.awayMessage
+		becameAutoAway = !wasAway && awayMessage != ""
 	}
 
 	if client.registrationTimer != nil {
@@ -1524,7 +1521,7 @@ func (client *Client) destroy(session *Session) {
 		client.server.stats.Remove(registered, invisible, operator)
 	}
 
-	if autoAway {
+	if becameAutoAway {
 		dispatchAwayNotify(client, true, awayMessage)
 	}
 
diff --git a/irc/getters.go b/irc/getters.go
index 5c1a43f5..2580683d 100644
--- a/irc/getters.go
+++ b/irc/getters.go
@@ -107,6 +107,7 @@ func (client *Client) AllSessionData(currentSession *Session, hasPrivs bool) (da
 }
 
 func (client *Client) AddSession(session *Session) (success bool, numSessions int, lastSeen time.Time, back bool) {
+	config := client.server.Config()
 	client.stateMutex.Lock()
 	defer client.stateMutex.Unlock()
 
@@ -126,11 +127,12 @@ func (client *Client) AddSession(session *Session) (success bool, numSessions in
 		client.setLastSeen(time.Now().UTC(), session.deviceID)
 	}
 	client.sessions = newSessions
-	if client.autoAway {
-		back = true
-		client.autoAway = false
-		client.away = false
+	// TODO(#1551) there should be a cap to opt out of this behavior on a session
+	if persistenceEnabled(config.Accounts.Multiclient.AutoAway, client.accountSettings.AutoAway) {
 		client.awayMessage = ""
+		if len(client.sessions) == 1 {
+			back = true
+		}
 	}
 	return true, len(client.sessions), lastSeen, back
 }
@@ -196,20 +198,54 @@ func (client *Client) Hostname() string {
 
 func (client *Client) Away() (result bool, message string) {
 	client.stateMutex.Lock()
-	result, message = client.away, client.awayMessage
+	message = client.awayMessage
 	client.stateMutex.Unlock()
+	result = client.awayMessage != ""
 	return
 }
 
-func (client *Client) SetAway(away bool, awayMessage string) (changed bool) {
+func (session *Session) SetAway(awayMessage string) {
+	client := session.client
+	config := client.server.Config()
+
 	client.stateMutex.Lock()
-	changed = away != client.away
-	client.away = away
-	client.awayMessage = awayMessage
-	client.stateMutex.Unlock()
+	defer client.stateMutex.Unlock()
+
+	session.awayMessage = awayMessage
+	session.awayAt = time.Now().UTC()
+
+	autoAway := client.registered && client.alwaysOn && persistenceEnabled(config.Accounts.Multiclient.AutoAway, client.accountSettings.AutoAway)
+	if autoAway {
+		client.setAutoAwayNoMutex(config)
+	} else {
+		client.awayMessage = awayMessage
+	}
 	return
 }
 
+func (client *Client) setAutoAwayNoMutex(config *Config) {
+	// aggregate the away statuses of the individual sessions:
+	var globalAwayState string
+	var awaySetAt time.Time
+	for _, cSession := range client.sessions {
+		if cSession.awayMessage == "" {
+			// a session is active, we are not auto-away
+			client.awayMessage = ""
+			return
+		} else if cSession.awayAt.After(awaySetAt) {
+			// choose the latest available away message from any session
+			globalAwayState = cSession.awayMessage
+			awaySetAt = cSession.awayAt
+		}
+	}
+	if awaySetAt.IsZero() {
+		// no sessions, enable auto-away
+		client.awayMessage = config.languageManager.Translate(client.languages, `User is currently disconnected`)
+	} else {
+		client.awayMessage = globalAwayState
+	}
+}
+
 func (client *Client) AlwaysOn() (alwaysOn bool) {
 	client.stateMutex.RLock()
 	alwaysOn = client.registered && client.alwaysOn
@@ -269,12 +305,6 @@ func (client *Client) AwayMessage() (result string) {
 	return
 }
 
-func (client *Client) SetAwayMessage(message string) {
-	client.stateMutex.Lock()
-	client.awayMessage = message
-	client.stateMutex.Unlock()
-}
-
 func (client *Client) Account() string {
 	client.stateMutex.RLock()
 	defer client.stateMutex.RUnlock()
diff --git a/irc/handlers.go b/irc/handlers.go
index ddd4d9c1..b910e1f1 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -352,7 +352,7 @@ func awayHandler(server *Server, client *Client, msg ircmsg.Message, rb *Respons
 		}
 	}
 
-	client.SetAway(isAway, awayMessage)
+	rb.session.SetAway(awayMessage)
 
 	if isAway {
 		rb.Add(nil, server.name, RPL_NOWAWAY, client.nick, client.t("You have been marked as being away"))
@@ -440,7 +440,7 @@ func brbHandler(server *Server, client *Client, msg ircmsg.Message, rb *Response
 
 	if len(client.Sessions()) == 1 {
 		// true BRB
-		client.SetAway(true, message)
+		rb.session.SetAway(message)
 	}
 
 	return true