sendmail configuration for a SMTP server

We were using an internal SMTP server and Matlab's sendmail functionality worked well. However, our SMTP server has changed and instead of smtp.companyname.com, we now have an ip address, say 10.23.154.2.

The new server doesn't require authentication and also no SSL connection. Still, we are not able to send emails

Version - R2013a

Old Config: setpref('Internet','SMTP_Server','smtp.xxx.com'), setpref('Internet','E_mail','XYZ')

New Config: setpref('Internet','SMTP_Server','10.23.154.2'), setpref('Internet','E_mail','XYZ')

As per IT team, telnet worked on the server and SMTP worked fine with IronPorts. Please comment.