How to Change/Move Domain smoothly

[ml at bortal.de]

Hello List,

i would like to change the MX record of a few domains.
Whats the best way to do this?

Right now i have set it to:
(...)
                                    2008060403
                                    15m     ;refresh
                                    1h     ;retry
                                    7d     ;expire
                                    1d    
(...)


Is this okay? Should i lower the retry time, too?
How can i check my changes with dig?

Thanks, Mario