I just got that email too. Being presented as a merger but DHL are much bigger worldwide so suspect it is more of a takeover with DHL looking to increase its share of small parcel business.

Perhaps typical of many parcel senders I use DHL for larger items and Royal Mail for small stuff, mostly afraid of Evri's reputation (although I believe it has improved over the last few years).

In my (rural) location DHL (deliveries and collections) turn up in a branded van, Evri deliveries turn up in a private car. Not sure how that pans out with a merged company.

Perhaps also preempting the inevitable shake up coming within Royal Mail now it's under new ownership of folding Parcel Force in and sharing resources.