Example from Nectar

A good example to maintaining deliverability when changing sending address from Nectar:
In the top of the email:
Don’t miss out! Ensure our emails reach your inbox by adding nectaronline@newsletter.nectar.com to your address book
Our email address is changing! Ensure our emails continue to reach your inbox by adding nectaronline@email.nectar.com to your address book

And then just after the main content but before the privacy blurb and opt-out…
Our email address is changing
Over the next few months we will be changing the email address that we use to send you communications like this one by email. If you receive an email from nectaronline@email.nectar.com and the images are not displaying or you’re not sure who it’s from, don’t worry – it’s still us sending the email.
All you have to do is add nectaronline@email.nectar.com to your address book or set the address as a safe-sender to ensure our emails still reach your inbox.

BUT..
NO external view link and what appears to be the main call to action does not have any links on it?
Also it would have been prudent to actually let the email address be a mailto link as email clients can allow addition to address book through the right click menu