A Microsoft extension to the ANSI SQL language that includes procedural programming, local variables, and various support functions.
I ran this query in msdb:
SELECT object_name(object_id), name
FROM sys.columns
WHERE name LIKE '%mail%'
It seems that there are columns in msdb you need to check.
To find references in stored procedures etc in a database, you can run:
SELECT object_name(object_id)
FROM sys.sql_modules
WHERE definition LIKE '%abc.com%'
Then the challenge is to run this on all your 250 servers, and on all databases (but the system databases) on every server. If you have not been using Powershell in your daily work, here is an excellent chance to get started!