Emails arrived in Outlook the next morning, so that was good. Email connectivity in relation to receiving was intermittent, however. Problem persisted through to Saturday morning, so called Slingshot helpline, after changing out modem etc. Helpline suggested changing out modem again, so did. Problem remained. Rang helpline again, who suggested that I buy a new modem. One has been ordered, but not sure if this is going to help.
Have connected another computer (laptop) directly to modem to rule out any local networking issues (problem remains).
Have used a Vodem to confirm that it is something to do with my ADSL connection (Vodem allows Outlook to receive Xtra emails just fine on same computer).
Slingshot uncapped plan. Good speed, reasonable pings.
I have tried 2x USR 9108 modems (my old favourites) and a CNet CAR-854 (which is pretty bollocks, but has been used here before and didn't exhibit any issues).
Have ordered a Netcomm NB304 at Slingshot's suggestion.
Internet browsing works fine.
I'm thinking that either:
(I) some ports are being blocked somewhere
(II) there was an upgrade to the local Telecom exchange and something was changed there.
Any suggestions? (I'm looking at you, Slingshot)