The initiative, manned by experienced production specialists, will offer over-the-phone support to agencies requiring immediate answers to production issues.
Production managers can ask for help with postage weight issues, difficult formats and pricing in proportion.
The helpline can also assist with campaign management and same-day service.
Production managers can call 08456 113399 from 8am until 5.30pm and calls will be charged at a local rate.
Tim Hamill, partnership director for marketing agencies at Royal Mail, said: "We are launching this new helpline in response to feedback we have received from direct marketing agencies over the last few months.
"Print production is a tough job requiring answers to niggling questions on an ongoing basis. Through the helpline we want to relieve some of this pressure and really add value to our client relationships."