Outlook / iphone - Cannot get rid of suggested contacts

Hi

I am trying to clean up my contacts in IOS 12.x

So my initial step was to reset the iPhone to factory defaults, keeping icloud off completely. So absolutely no contacts on the pjhone at all.

Then I cleaned up my personal contacts in Outlook to just what I want. Then I deleted my autocomplete file in my profiles roamcahce directory. No suggestions are put forward when I type a letter in a new email. So far so good.

So now I set up my Exchange account which went OK. When I start to type an email address on my iPhone it shows literally hundreds of old emails addresses which I was trying to delete. Looking at the contacs app under contacs there are just my Outlook contacs, good, but there is another group called suggested contacts which contains all these mails. Even if I deselect this group and just have contacts ticked , when I start typing an address it shows everything.

Where is this junk stored in Outlook? It is not the autocomplete file as I deleted that. It must be outlook as I did an iPhone fiull erase and reset, set up as a new phone and made sure nothing Icloud was enabled. To be sure I user my laptop to log into icloud to check what contacts I had there and there were only 4.

Any ideas please?

Thanks

Aladair Barclay