sms textemail messages showing up late

I had an outage where serverscheck correctly generated 300+ smsemail alerts. After about an hour and the alert situation was fixed, serverscheck dashboard showed zero rules in warning or down but I was still receiving smsemail messages of alerts that happened 60 miuntes ago. I went into the alertsqueue directory and there were 200+ *.alert files slowly being processed. I deleted all the .alert files and restarted serverscheck and that fixed the issue. Any ideas on why it was so slow sending alerts?

SMS alerting is one after the other (sequential) due to the nature of the mobile phone protocol.