error in squirlmail

[Nexxterra.com]

With NO changes to the server, all of a sudden I am getting this message when attempting to send email.
"Message not sent. Server replied:
Requested action not taken: mailbox unavailable
550 relay not permitted, authentication required"
this error is server wide and again occurred with NO changes or updates.
server has exim and dovecot
Also, sending and receiving in outlook works fine.

 

[scsi]

Well something had to of changed if localhost cant relay anymore

Check if you get the error in other webmail clients like atmail or roundcube

 

[Nexxterra.com]

No other webmail

there was 2 other, Roundcube, removed a couple of years ago, and UBimaui (or something like that) removed about 3 years ago
An explanation of the error message might be a good start???
Is this an exim issue? an issue with Squrril? what....
I of course have searched the logs for errors and changes... NONE!

 

[scsi]

Well something is wrong in your exim.conf or in the squirrelmail config. If it cannot relay localhost connections then something is wrong. The error is from the exim server.