How safe is it to send email with matlab using sendmail?

I'm planning to send several emails via Matlab using the built in sendmail function. I would like to know first if there is any security issue related to the fact that the password associated to the email account that is used has to be stored somewhere in Matlab.

Let's say I first enter my password to send an email and then I "erase" it as following (closing matlab does not reset internet preferences):

pwd = inputdlg('password'); pwd=pwd{1};
setpref('Internet','SMTP_Password',pwd);
sendmail('[e-mail]',subject,body);
setpref('Internet','SMTP_Password','');

I would like to be certain that the password is not stored anywhere else. Thanks in advance.