diff --git src/bp-core/bp-core-filters.php src/bp-core/bp-core-filters.php
index 85a8978d2..2f8a196de 100644
--- src/bp-core/bp-core-filters.php
+++ src/bp-core/bp-core-filters.php
@@ -473,15 +473,9 @@ function bp_core_activation_signup_blog_notification( $domain, $path, $title, $u
 		),
 	);
 
-	$signups = BP_Signup::get(
-		array(
-			'user_login' => $user,
-		)
-	);
-
+	$signup     = bp_members_get_signup_by( 'activation_key', $key );
 	$salutation = $user;
-	if ( $signups && bp_is_active( 'xprofile' ) ) {
-		$signup = $signups['signups'][0];
+	if ( $signup && bp_is_active( 'xprofile' ) ) {
 		if ( isset( $signup->meta[ 'field_' . bp_xprofile_fullname_field_id() ] ) ) {
 			$salutation = $signup->meta[ 'field_' . bp_xprofile_fullname_field_id() ];
 		}
@@ -563,6 +557,31 @@ function bp_core_activation_signup_user_notification( $user, $user_email, $key,
 }
 add_filter( 'wpmu_signup_user_notification', 'bp_core_activation_signup_user_notification', 1, 4 );
 
+/**
+ * Ensure that some meta values are set for new multisite signups.
+ *
+ * @since 10.0.0
+ *
+ * @see wpmu_signup_user() for a full description of params.
+ *
+ * @param array $meta Signup meta data. Default empty array.
+ * @return array Signup meta data.
+ */
+function bp_core_add_meta_to_multisite_signups( $meta ) {
+
+	// Ensure that sent_date and count_sent are set in meta.
+	if ( ! isset( $meta['sent_date'] ) ) {
+		$meta['sent_date'] = '0000-00-00 00:00:00';
+	}
+	if ( ! isset( $meta['count_sent'] ) ) {
+		$meta['count_sent'] = 0;
+	}
+
+	return $meta;
+}
+add_filter( 'signup_user_meta', 'bp_core_add_meta_to_multisite_signups' );
+add_filter( 'signup_site_meta', 'bp_core_add_meta_to_multisite_signups' );
+
 /**
  * Filter the page title for BuddyPress pages.
  *
diff --git src/bp-members/bp-members-functions.php src/bp-members/bp-members-functions.php
index 93fd7cafd..ec4e651ed 100644
--- src/bp-members/bp-members-functions.php
+++ src/bp-members/bp-members-functions.php
@@ -2388,24 +2388,18 @@ function bp_core_signup_send_validation_email( $user_id, $user_email, $key, $sal
 	bp_send_email( 'core-user-registration', $to, $args );
 
 	// Record that the activation email has been sent.
-	$signups = BP_Signup::get(
-		array(
-			'activation_key' => $key,
-		)
-	);
+	$signup = bp_members_get_signup_by( 'activation_key', $key );
 
-	if ( ! empty( $signups['signups'] ) ) {
-		foreach ( $signups['signups'] as $signup ) {
-			$meta = array(
-				'sent_date'  => current_time( 'mysql', true ),
-				'count_sent' => $signup->count_sent + 1
-			);
+	if ( $signup ) {
+		$meta = array(
+			'sent_date'  => current_time( 'mysql', true ),
+			'count_sent' => $signup->count_sent + 1
+		);
 
-			BP_Signup::update( array(
-				'signup_id' => $signup->id,
-				'meta'      => $meta,
-			) );
-		}
+		BP_Signup::update( array(
+			'signup_id' => $signup->id,
+			'meta'      => $meta,
+		) );
 	}
 }
 
@@ -3694,3 +3688,42 @@ function bp_get_members_invitation_from_request() {
 	 */
 	return apply_filters( 'bp_get_members_invitation_from_request', $invite );
 }
+
+/**
+ * Get BP_Signup object corresponding to a record in the signups table.
+ *
+ * @since 10.0.0
+ *
+ * @param string $field Which fields to search by. Possible values are
+ *                      activation_key, user_email, id.
+ * @param string $value Value to search by.
+ * @return bool|BP_Signup $signup Found signup, returns first found
+ *                                if more than one is found.
+ */
+function bp_members_get_signup_by( $field = 'activation_key', $value = '' ) {
+	switch ( $field ) {
+		case 'activation_key':
+		case 'user_email':
+			$key = $field;
+			break;
+
+		case 'id':
+		default:
+			$key = 'include';
+			break;
+	}
+
+	$signups = BP_Signup::get(
+		array(
+			$key => $value,
+		)
+	);
+
+	if ( ! empty( $signups['signups'] ) ) {
+		$signup = current( $signups['signups'] );
+	} else {
+		$signup = false;
+	}
+
+	return $signup;
+}
diff --git src/bp-members/classes/class-bp-members-admin.php src/bp-members/classes/class-bp-members-admin.php
index 979847a18..eadd2572a 100644
--- src/bp-members/classes/class-bp-members-admin.php
+++ src/bp-members/classes/class-bp-members-admin.php
@@ -2204,7 +2204,7 @@ class BP_Members_Admin {
 		) );
 
 		$signups    = $signups_query['signups'];
-		$signup_ids = wp_list_pluck( $signups, 'signup_id' );
+		$signup_ids = wp_list_pluck( $signups, 'id' );
 
 		// Set up strings.
 		switch ( $action ) {
diff --git src/bp-members/classes/class-bp-signup.php src/bp-members/classes/class-bp-signup.php
index 9de2af9fe..e48d21da4 100644
--- src/bp-members/classes/class-bp-signup.php
+++ src/bp-members/classes/class-bp-signup.php
@@ -214,6 +214,17 @@ class BP_Signup {
 			$this->date_sent = $signup->registered;
 		}
 
+		// How many times has the activation email been sent?
+		if ( isset( $this->meta['count_sent'] ) ) {
+			$this->count_sent = absint( $this->meta['count_sent'] );
+		} else {
+			/**
+			 * Meta will not be set if this is a pre-10.0 signup.
+			 * In this case, we assume that the count is 1.
+			 */
+			$this->count_sent = 1;
+		}
+
 		/**
 		 * Calculate a diff between now & last time
 		 * an activation link has been resent.
@@ -226,14 +237,8 @@ class BP_Signup {
 		 * Set a boolean to track whether an activation link
 		 * was sent in the last day.
 		 */
-		$this->recently_sent = ( $diff < 1 * DAY_IN_SECONDS );
+		$this->recently_sent = $this->count_sent && ( $diff < 1 * DAY_IN_SECONDS );
 
-		// How many times has the activation email been sent?
-		if ( isset( $this->meta['count_sent'] ) ) {
-			$this->count_sent = absint( $this->meta['count_sent'] );
-		} else {
-			$this->count_sent = 0;
-		}
 	}
 
 	/** Static Methods *******************************************************/
@@ -814,14 +819,18 @@ class BP_Signup {
 
 		foreach ( $signups as $signup ) {
 
-			$meta = array(
-				'sent_date'  => current_time( 'mysql', true ),
-				'count_sent' => $signup->count_sent + 1
-			);
+			$meta               = $signup->meta;
+			$meta['sent_date']  = current_time( 'mysql', true );
+			$meta['count_sent'] = $signup->count_sent + 1;
 
 			// Send activation email.
 			if ( is_multisite() ) {
-				wpmu_signup_user_notification( $signup->user_login, $signup->user_email, $signup->activation_key, serialize( $meta ) );
+				// Should we send the user or blog activation email?
+				if ( ! empty( $signup->domain ) || ! empty( $signup->path ) ) {
+					wpmu_signup_blog_notification( $signup->domain, $signup->path, $signup->title, $signup->user_login, $signup->user_email, $signup->activation_key, $meta );
+				} else {
+					wpmu_signup_user_notification( $signup->user_login, $signup->user_email, $signup->activation_key, $meta );
+				}
 			} else {
 
 				// Check user status before sending email.