Can anybody suggest a reasonably-priced autoresponder (either web-based or installed on the site) that is above all reliable and does exactly what it says (I have had some relally bad experience with unreliable ones recently). Many thanks.

Any decent web-host will supply that at no extra cost.

What I am intrested in is an autoresponder service with follow up messages ability and ohter features like multiple accounts, importing, exporting, customised forms etc.
thanks

Do a Google with email autoresponder and be surprised...