I am using text variable manipulation to construct customized plain text and HTML email messages for hundreds of thousands of customers...no two email messages are the same...each email message has a completely different product mix.
Through the use of a forward-read-only cursors, the entire mail-merge process of 35kilobyte-50kilobyte sized email messages can be completed in well under 3 hours.
Text data manipulation on a SQL Server platform is very, very fast and requires no additional software to be used. I've built other solutions but none have come close to matching the mail-merging speed of performing text data manipulation on the SQL Server box itself.
Text data manipulation is a skill very much worth learning.