How do I send email with SSL

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Cannot send email with SSL
ServerSMTP and portSMTP 465 are ok
tested with smtp.gmail.com 465 sslSMTP=true
Matybe something related to TSL_1.1/1.2 ?

What I have tried:

Dim SmtpClient As New SmtpClient(ServerSMTP, portSMTP)
Dim mail As New MailMessage()
SmtpClient.EnableSsl = sslSMTP
SmtpClient.Timeout =2000
SmtpClient.UseDefaultCredentials = False
SmtpClient.Credentials = New Net.NetworkCredential(UserSMTP, pswSMTP)
mail.From = New MailAddress(mittente)
For i As Integer = 0 To Destinatari.Length - 1
    mail.To.Add(Destinatari(i))
Next
mail.Subject = Oggetto
mail.IsBodyHtml = IsHtml
mail.Body = Corpo
SmtpClient.Send(mail)

Posted 4-Dec-22 1:56am

BigMax

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Comments

Michael_Davies 4-Dec-22 8:12am

What is the error message, add a Try Catch around the send and catch the error message.

I have similar code using Gmail, apart from actual values, the only extra I add is the SMTPClient Delivery method set to Network but not likely to be a problem.

BigMax 4-Dec-22 8:30am

InnerException = {"Impossibile leggere dati dalla connessione del trasporto: net_io_connectionclosed."}

Impossible to read data from transport connection

BigMax 4-Dec-22 8:26am

thx Michael, yes its in try-catch

in System.Net.Mail.SmtpReplyReaderFactory.ProcessRead(Byte[] buffer, Int32 offset, Int32 read, Boolean readLine)
in System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine)
in System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller)
in System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)
in System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint)
in System.Net.Mail.SmtpClient.GetConnection()
in System.Net.Mail.SmtpClient.Send(MailMessage message)

Michael_Davies 4-Dec-22 9:17am

Looking at MS documentation they recommend not using SMTPClient but Mailkit instead, for reasons of security (looks like I'll have to update my old app.).

https://stackoverflow.com/questions/20228644/smtpexception-unable-to-read-data-from-the-transport-connection-net-io-connect

BigMax 4-Dec-22 9:56am

yes, downloading Mailkit
thx have a nice day

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