I have given up on using Zoho Mail for custom email addresses, but have just discovered a different service: Yandex.Connect. This provides what is seemingly the same service as Zoho Mail, except it allows .tk, .ml, .ga, .gq and .cf domains (notice that these are all of the free ones from Freenom) - although when you sign up, make sure you do it through connect.yandex.com, as opposed to domain.yandex.com, which is an older service (they are migrating to Yandex.Connect) that doesn't allow all of the free domains. Yandex.Connect is a free service, with unlimited mailboxes of an unlimited size (as far as I know); I have now got a customised personal email address ([email protected]), along with ones for www.aquapi.ml and www.blackthunder.ga (a water-saving project and Reading School's Robotics Club, respectively).
You may have noticed that I'm rather keen on finding money-saving (i.e. free) ways of doing normally costly things. So far, I have 8 domains, three of which have customised email addresses, and web hosting - all for free, instead of a possible £400 or more! And now, with the release of Chrome 68 (which flags all websites served over HTTP as "insecure" with a rather large message), I decided I needed an SSL certificate. I didn't realise that they could be obtained for free - yet they can! I set up Cloudflare, which involves a really simple procedure: change the nameservers to those of Cloudflare and check all of your DNS records are kept by Cloudflare. This means that all alterations to DNS records have to be done through the Cloudflare website, which has a better control panel than Freenom anyway (in my opinion), as the nameservers have changed.
Finally, as I was browsing the net, I came across the idea of custom shortened URLs. As it turns out, Bitly (a service which I already used, and you have most likely heard of) natively supports 'Branded Shorts Domains' (BSDs), which is great! With the basic (free) Bitly account, you get one BSD and all you have to do is add two A records in the DNS (and a CNAME if you want to use the www subdomain too), and then carry on using Bitly as normal!