Hello,

error code :

550 Verification failed for mail

This error will occur if exim cannot verify the sending email address.
This might be because the domain doesn't return an MX record, or the email account itself doesn't exist.

To disable the check following are the steps :

Code:
root@server01[~]#vi /etc/exim.conf
Change

require verify = sender

to

#require verify = sender
And then restart exim service.

Code:
root@server01[~]#service exim restart
Regards,
Silvester J