Originally Posted by
Redhead
While the Mexican Immigration authorities may not have asked you, the airlines do reserve the right to deny you boarding if you can't provide proof of onward travel plans.
This is what she said to me.. that they are obligated to check for onward passage before boarding you on your outbound...otherwise they could be fined by Mexican immigration. So whether Mexican immigration checks or not is not the issue....and if your reservation is showing RT the issue will never come up.