Error - Need a valid email address

[gulas]

Hello All,

suddently my OTRS stop working well..
when i try to reply a ticket, it takes so long to open, and then says: one or more errors("Need a valid email address or dont use a local email address"). The email is correct.
it was working well and i didnt change anything

What is the problem ? and what can i do ?

Thanks

[jojo]

Have a look in the log files

[gulas]

It seems to be a problem with DNS.. Im using gmail account.

thanks