In an e-mail to those under the airline’s frequent flyer program MileagePlus, Munoz made a number of promises to restore faith in a carrier that has been the subject of some negative press of late, but made no explicit mention of Smisek, who resigned amid an investigation over his dealings with a New York area transit official.

“We can do better, and will keep listening to our customers to become the top-performing airline,” Munoz wrote.

He also indirectly addressed long-standing operational issues, topped by a recent scorecard that put United in last place among all major U.S. airlines in service-related categories. United’s ranking in on-time arrivals, cancellations, and two-hour runway delays all worsened over the past year, and Munoz assured customers that the carrier would improve.

“Getting you to your destination, on schedule, can make or break your ability to succeed in a work endeavor or to hug a family member at an important moment. If our performance has not met your expectations, I want you to know I’m committed to learning how to better meet your needs and desires,” he said.

The e-mail, however, curiously lacks any contact information for flyers to provide feedback to Munoz and his team on where exactly they should improve. Fortune has reached out to United for further details on this.

Smisek lost his job after a federal investigation into the role of former Port Authority Chairman David Samson in the allegedly politically-motivated lane closure incident on the George Washington Bridge uncovered a shady agreement between both men. They were both central characters in the resurrection of the Newark-Columbia route, which Samson reportedly requested as it was near his weekend home. In exchange, Smisek reportedly wanted major upgrades to the Newark Liberty International Airport, a central United hub.

Update: United responded to observations about the lack of a feedback contact through spokesman Rahsaan Johnson:

Pursuant to your specific question, we also saw feedback online that it was odd that we would send a letter soliciting feedback from an email address that couldn’t take responses. Given that we sent the letter to millions of customers, we could not constructively reply if potentially millions of people hit reply to provide feedback.

Johnson said the email from Munoz was an introductory step in a long process. He added customers who would like to offer feedback on improvements to United can go through the pre-travel customer channels or fill out the post-travel customer feedback form found here.