buongiorno a tutti,
ho creato una pagina aspx che consente al cliente finale di creare ed inviare newsletter.
la pagina è online da + di 2 anni, ma da oggi quando si tenta di inviare la mail creata esce il seguente errore:
Server Error in '/' Application.
Exceeded storage allocation. The server response was: 5.2.0 Y8Vy1m01F53awDq018Vyzq spam detected
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Net.Mail.SmtpException: Exceeded storage allocation. The server response was: 5.2.0 Y8Vy1m01F53awDq018Vyzq spam detected

Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:
[SmtpException: Exceeded storage allocation. The server response was: 5.2.0 Y8Vy1m01F53awDq018Vyzq spam detected]
System.Net.Mail.DataStopCommand.CheckResponse(Smtp StatusCode statusCode, String serverResponse) +1061699
System.Net.Mail.DataStopCommand.Send(SmtpConnectio n conn) +38
System.Net.Mail.SmtpConnection.OnClose(Object sender, EventArgs args) +8
System.Net.ClosableStream.Close() +53
System.Net.Mail.MailWriter.Close() +53
System.Net.Mail.SmtpClient.Send(MailMessage message) +1480
newsletter.BtInvia_Click(Object sender, EventArgs e) +5507
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +111
System.Web.UI.WebControls.Button.RaisePostBackEven t(String eventArgument) +110
System.Web.UI.WebControls.Button.System.Web.UI.IPo stBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEve ntHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCol lection postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565

Version Information: Microsoft .NET Framework Version:2.0.50727.3649; ASP.NET Version:2.0.50727.3634

l'errore esce anche se vado a prendere newsletter vecchie che erano partite benissimo.
sicuramente è un problema di spam ma non so più che pesci pigliare.
l'smtp che uso è di aruba

grazie a tutti