{"id":5524,"date":"2022-02-06T21:54:55","date_gmt":"2022-02-06T21:54:55","guid":{"rendered":"https:\/\/pariswells.com\/blog\/?p=5524"},"modified":"2022-02-16T00:38:34","modified_gmt":"2022-02-16T00:38:34","slug":"asp-net-c-project-to-send-e-mail-via-office-365-starts-firing-net_io_connectionclosed","status":"publish","type":"post","link":"https:\/\/pariswells.com\/blog\/research\/asp-net-c-project-to-send-e-mail-via-office-365-starts-firing-net_io_connectionclosed","title":{"rendered":"ASP.NET C# project to send e-mail via Office 365 starts firing net_io_connectionclosed"},"content":{"rendered":"

System.IO.IOException: Unable to read data from the transport connection: net_io_connectionclosed. at System.Net.Mail.SmtpReplyReaderFactory.ProcessRead(Byte[] buffer, Int32 offset, Int32 read, Boolean readLine) at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine) at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller) at System.Net.Mail.CheckCommand.Send(SmtpConnection conn, String& response) at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception) at System.Net.Mail.SmtpClient.Send(MailMessage message)<\/p>

Need to change ASP to use TLS 1.2 as Microsoft of EOL TLS1.1 and rejecting emails occasionally to remind you of this!\u00a0<\/strong><\/p>

Upgrading the .net Framework to 4.6 and over will fix this<\/p>

This the web.config file for this :\u00a0\u00a0<\/p>

<system.web>
<compilation targetFramework=”4.6″\/> <!– Changed framework from Under 4.5 to 4.6 or 4.7 –>
<!–Added this httpRuntime –>
<httpRuntime targetFramework=”4.6″ \/>
<\/system.web><\/p>

<\/code><\/p>","protected":false},"excerpt":{"rendered":"

System.IO.IOException: Unable to read data from the transport connection: net_io_connectionclosed. at System.Net.Mail.SmtpReplyReaderFactory.ProcessRead(Byte[] buffer, Int32 offset, Int32 read, Boolean readLine) at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine) at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller) […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3500,3713,598,3568,571,3714,3715,2350],"class_list":["post-5524","post","type-post","status-publish","format-standard","hentry","category-research","tag-1-1","tag-1-2","tag-asp","tag-net_io_connectionclosed","tag-office-365","tag-system-io-ioexception","tag-system-net-mail-smtpreplyreaderfactory","tag-tls"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t