Thanks. Yes I can only think that my rules have undermined the provider's spam filter. It is an IMAP connection and the rules were set up using the 'create rule' option, I have MS Office 2019. The reduction has been startling. Now on day 2 and there are a handful of items in the junk folder and only a couple in the inbox. Previously 50 a day was typical in the junk folder. Lots of the junk came from a constantly changing .rdl address with many from 'friki something'. They were crafty, adding changing punctuation marks to key words to evade the rule test, hence the proliferation of rules.
Thanks for your collective advice, lesson learnt. A bit of a pity as it negates the Outlook feature but there you go. There was me thinking I was doing the right thing....