Difference between Database mail and SQL Mail

Database mail is the email system introduced from SQL 2005 onwards and SQL Mail is the promary email system available upto SQL 2000. However SQL Mail can still run in SQL 2005 and SQL 2008 in legacy mode provided administrtor explicetely enables it by executing below procedure:

EXEC sp_configure 'SQL Mail XPs', 1

There are distinct differences between Database mail and SQL Mail. Database mail is replacement of SQL Mail with many enhancements. Database Mail is based on SMTP (Simple Mail Transfer Protocol) and is very fast and reliable where SQL Mail is based on MAPI (Messaging Application Programming Interface) which is slower. Database Mail can be encrypted for additional security. SQLMail is less secure as it can not be encrypt the message. Also anybody can use SMTP to send email using SQL Mail.

Additionally, for SQLMail you need to enable MAPI on a server which requires Outlook to be installed. Installing any office component is a security hazard for a server. However on the other hand Database mail depends on Service Broker so this service must be enabled for Database Mail.

Considering these difference, it is highly recommended to migrate everything to Database Mail and stop using SQL Mail.