Time to get yourself ISP-independent email. Either free gmail or Microsoft Outlook (ex hotmail) or if like me you don't fancy those pay a small amount for a domain and a mail service.
Usually all working within minutes of doing that.
In your case, today!.
I use Tsohost (now owned by GoDaddy) and ionos (ex 1 & 1). Both are fine. For years it was just Tsohost but then I needed a lot more web and mail space and that got expensive with them. Ionos is also getting more expensive for space but at the moment I'm on a legacy cheap completely unlimited web space product. Until they decide to "retire" it of course.
A once-off hassle is letting all important contacts know the new one, but you ease the pressure by telling them using the
Plusnet one and asking them to acknowledge to the new one. You can do that over a few days starting with the frequent ones.
No need to tell most commercial contacts. Just change it in your account details with them. They should be given a unique "alias" so if you get spam to that address you know where it leaked from so can block it and change it again in your account with them. Which you can't do with a standard ISP-based address. Good providers allow unlimited aliases.
Start sending (and replying) purely from your domain but continue to listen to both the new and old ones until you are confident nobody is sending to the ISP address. (Possibly you can set the ISP one to forward to the domain anyway).
The problem of your email address if you migrate to another ISP is solved for ever. Nobody needs to know.
Similarly, changing your email provider is not a biggy, as you can fairly easily move the domain host if you wish or just leave it where it is and change the name server links in the domain account. The two do not have to be with the same provider.
Connections: OnePlus 8 Pro on Three 4+ (LTE)/5G and at home Three Mobile, with (Three)ZTE MF286D router giving about 113/20Mbps.
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The price of liberty, and even of common humanity, is eternal vigilance. (Aldous Huxley version of the well-known saying)
Were there none who were discontented with what they have, the world would never reach anything better. Florence Nightingale (Cassandra: an Essay (1860 edition?)