You can legally send them but the recipient will probably end up paying more for them than if he/she had simply gone to the nearest supermarket.
Excise duty is payable on all imports of cigarettes (even if they're gifts). Import duty and VAT are waived for bona fide gifts containing no more than 50 cigarettes but become payable thereafter. There's also a customs examination fee of £8 to be paid.
Slight correction:
Excise duty is payable on imports of cigarettes from within the EU but import duty and VAT aren't.
So if the cigarettes are sent from Spain the recipient will have to pay (on 200 cigarettes) about £32 in Excise Duty, plus £8 postal examination fee. However if the cigarettes were sent from the Canary Islands (which are regarded as non-EU for customs purposes, because of their special tax staus) there would be far more to pay.
Postal imports from within the EU are not routinely opened for customs inspection (as imports from non-EU countries are). However packages which might possibly contain tobacco or alcohol (which are still subject to excise duty, even if sent from within the EU) can be opened. It's likely that the sniffer dogs which are trained to indicate the presence of drugs within postal items are also trained to alert staff to the presence of tobacco.
So is there a difference between some posting me 400 cigarettes from France and me going over and bringing them back personally, when I would have no further duty to pay?
The 'unlimited quantity for personal use' rule (with a guideline maximum of 3200) only applies to personal imports. See here:
http://tinyurl.com/2f9apm6
Having just re-read my own link, I now find that VAT (as well as excise duty) is chargeable on postal tobacco imports within the EU. So the recipient of Netibiza's 200 ciggies from Spain will have even more to pay than the £40 suggested in my post above!
Oh dear, "The road to Hell etc etc", shan't bother again as the postage was bad enough. Thank you all very much. I was talking duty paid and hoped that would make a difference!!