I have a Java web application using Apache & Tomcat on a Linux server with SendMail as my mail server. After years without an issue, I have suddenly experienced wide performance swings when sending out an email via my web app. From < 1 second to > 20 seconds. It is very sporadic and on some days it is consistently really slow ( > 30 seconds). Any ideas on how/why this could happen and what can be done about it?