In that situation retrying to the low numbered (high priority) mx server 
is probably the correct option so I think it's better that it keeps 
retrying, sending to the other server may work but won't result in the 
recipient getting the  message so isn't really an improvement.  
g_mx_tryall may help in that situation, if you want it to do that, I 
don't recommend it.

ChrisP.


On 19/02/2016 9:16 p.m., surgemailHIDDEN@etwinsite.com wrote:
> Hi,
>
> I found some dump smtp server that has 2 mx servers, surgemail sending to lower mx priority (5) keep return temporary fail (code 451) for more than 3 hours in mail queue but when try to manual change to new one with higher priority (10) it successful send without retry.
>
> I don't know if surgemail has this config or not and I am not sure about g_mx_tryall
>
> Thank you
> Pisit