replacing a string on smtp traffic (adding suffix)

hey i have a pool of smtp servers

 

and i have an issue that my users are sending the recipient address without a suffix

 

and my smtp relay cannot accept that

 

 

 

i need to create an irule that adds a suffix on an email address

 

 

for example

 

 

mail from: adam@smtpexample.com

 

 

rcpt to: adam@exmaple

 

 

replace string

 

 

mail from: adam@123example.com (don't change)

 

 

rcpt to:adam@example.com

 

 

 

any suggestions