note that your trigger must handle multiple rows - the trigger (in Microsoft SQL at least ...) is only called once regardless of the number of rows processed in the INSERT / UPDATE / DELETE statement. It seems likely that your Trigger will usually be called with a single row each time, but you still need to allow for multi-row actions (at the least you could raise an error if multiple rows are received by the trigger)
For your EMail routine you would therefore have to loop round each row that the trigger receives. This question is raised quite often and the usual advice is that a trigger needs to be fast, and "slim". Calling a (Synchronous) EMail Stored Procedure, which may sit-and-wait for an SMTP server to say "Hello" to a remote server, retry a few times, is not a good candidate for a trigger.
The usual answer is to use the trigger to save the data into a "queue" (a table for that purpose, or something which will manage a queue like Service Broker). If your trigger is already "copying" the data into an Audit Table one solution might be to have some extra columns in the Audit Table:
Date/Time EMail sent
Email Result Code - e.g. 0=Success, non-zero = Error Code
and then have something else periodically (every second or two if you like) check the Audit Table for new rows WHERE [Date/Time EMail sent] IS NULL and then send the email, then update [Data/Time EMail sent] to current date/time, and [Email Result Code] to the return value from sp_send_dbmail. That routine might be somethng like this:
DECLARE @ID int, @ErrNo int, @Col1 ..., @Col2 ..., ...
SELECT TOP 1 @ID = ID, @Col1 = col1, @Col2 = col2, ...
WHERE [Date/Time EMail sent] IS NULL
ORDER BY [Date/Time Created]
IF @@ROWCOUNT = 0 GOTO NoMoreRowsToProcess
SELECT @EmailBody = 'Record ID=' + CONVERT(varchar(20), @ID) + ' has changed'
-- Incorporate @Col1, @Col2 etc. in the body of the message as appropraite
EXEC @ErrNo = msdb.dbo.sp_send_dbmail
-- Mark the Email as sent / error code
SET [Date/Time EMail sent] = GetDate()
[Email Result Code] = @ErrNo
FROM YourAuditTable AS U
WHERE ID = @ID