We still do direct mail. Not on a monthly basis, but every few months we send out a few thousand on behalf of our clients.
We used to use third party companies, but they were charging around $3 a letter including the postage and we can do it in-house for $0.90 a letter including the postage. We passed the savings onto the client and doubled down into quality papers, etc when they were willing to spend more.
The key things when working with a company for direct mail (from our perspective):
1. How much do they charge to clean lists?
2. How fast can they go from receiving the files to hitting mailboxes?
3. Do they offer design services or are we supplying the designs?
4. Do they openly offer up the pricing for AdMail vs Regular mail with the benefits of each? (might be a Canada Post thing)
5. Do they have options for labelling the envelopes?
6. Do they have consistent enough pricing that I can resell without requiring a quote each time?
Other small issues, but after working with 6 different printers and 2 different direct mail companies, I've come to realize where the pain points are, what costs me more money and what information tends to show experience in doing what we need done.
For us though, turnaround time is king.