These Footsie stocks are dealing at multi-year lows. Are they now perfect dip buys?

The share value of Royal Mail(LSE: RMG) shuttled to its cheapest since December 2014 last week after a less-than-enthusiastic reception to its latest trading update.

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The terminal decline in the letters market was again laid bare by the release, with letter volumes -- excluding the impact of election-related correspondence -- sinking 6% during April-December. The firm commented that "we are seeing the impact of overall business uncertainty in the UK on letter volumes, in particular advertising and business letters."

But the City believes Royal Mail's bottom line is about to turn higher regardless of this week's patchy results, helped in no small part by resilient parcels traffic.

Following an anticipated 2% earnings decline in the year to March 2017, the courier is expected to record a marginal uptick in 2018, which is expected to mark a sustained return to earnings growth.

These figures are certainly not enough to get too excited about. But after recent share price weakness they leave the courier changing hands on P/E ratios of just 10 times through to the end of fiscal 2018. It could be argued that the near-term risks facing Royal Mail are baked-in at current share prices.

And the parcels play also provides excitement for income chasers. Despite forecasts that earnings will remain broadly flat during the next few years, the impact of extensive restructuring on Royal Mail's balance sheet is expected to keep blasting dividends higher.

For 2017, a payment of 23p per share is estimated, yielding an exceptional 5.7%. And a predicted dividend of 23.7p for 2018 yields 5.8%.

With e-commerce set to blast parcels volumes through the roof in the years ahead, and Royal Mail's GLS arm also making waves on the continent, I reckon Royal Mail could prove a hugely-lucrative stock for long-term investors.

Hang ups

News of huge accounting irregularities at BT Group (LSE: BT-A) dominated the financial papers last week. The news saw the telecoms titan shed more than a fifth of its share value on the day of the release alone, and BT is now changing hands at levels not seen since June 2013.

To recap, the company announced that bad accounting practices at its Italian division have created a colossal £530m black hole, much worse than the £145m estimated back in October. The scandal has prompted BT's European head Corrado Sciolla to fall on his sword, and has prompted a number of management suspensions at BT Italy.

But some investors jumped back in on Friday in the hope of snapping up a bargain. While BT is expected to endure a 10% earnings fall in the year to March 2017, this projection leaves the business dealing on a P/E ratio of just 10.1 times. And City predictions of a 7% rise in fiscal 2018 pushes the multiple to an even-better 9.4 times.

And broker forecasts suggest that dividend chasers should also check out the stock. Anticipated payouts of 15.4p and 17p per share in 2017 and 2018 respectively yield 5.1% and 5.6%.

That said, I believe share pickers should think twice before diving in at the current time.

Not only could BT's forthcoming, group-wide review into financial practices throw up fresh trouble, but there are signs of slowing business at its UK operations. The company also warned of "a more challenging outlook in the UK public sector and international corporate markets" last week. This could also put the firm's share price back on the defensive.

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Royston Wild has no position in any shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.