Self Registration Module, what to do it email does not get to user?

[AHH]

Hi,

My server settings are as follows:

CMS Made Simple 1.2.4 "Greenland"
Operating system: Linux
MySQL version :      5.0.45-community
Apache version  : 2.0.63
PHP version   :      5.2.5

I am using Self Registration Module 1.2
{cms_module module=SelfRegistration group=Candidates}

Candidates have to register using email verification.  I find that some emails do not get to candidates for various reasons.  The problem I have is what to do if the email does not get to the candidate. 

Is there a way to manually move the user from the Self Registration Module to the Front End User module using the interface?  I am also experiencing problems if I edit a users details in the Self Registration Module before they have completed the registration process and check send email to user.  These emails are not being sent.  I have tested registering and the module sends that email, also tested CMSMailer and the test email from that came through correctly. 

Not sure what to check or how to proceed from here, please help with this.

Thanks
Aden