Each day we send out a newsletter and every day some sendout fails.
We use AWS email service as provider.
In the newsletter studio backend I've got this errormessage
Service not available, closing transmission channel. The server response was: Timeout waiting for data from client. at System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, 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)
at NewsletterStudio.Services.Mail.NsSmtpClient.Send(MailMessage mail)
at NewsletterStudio.Services.SendNewsletterService.SendEmails()
What does that mean? Is it related to AWS, spamfilter or something else?
The email adresses that fails, are existing emailadresses that i'm able to send a emailmessage to, hrough a normal email client
Each day we send approx. 500 emails. Around 15-20 of them fail, and most of the failed emails have the listed error, so our configuration is functional ("Test connection" is OK).
With a "normal email client" i menat Outlook and gmail.
Ontop of Markus's query, there may be a limit into SMTP server that is designed to prevent spam sendings.
It could be worth checking with them as the error you are referring to indicates that the .NET SMTP client is timing out during the send process when it is waiting for confirmation from the SMTP server itself.
In the past I've seen this error when too many individual emails have been sent to an SMTP relay that isn't designed for bulk distribution.
We send out around 1K every day. We have a limit of 50 emails/second but we shouldn't hit the limit. We batch the emails in code and limit them to 10 per second.
What does this error mean
Each day we send out a newsletter and every day some sendout fails.
We use AWS email service as provider.
In the newsletter studio backend I've got this errormessage
What does that mean? Is it related to AWS, spamfilter or something else?
The email adresses that fails, are existing emailadresses that i'm able to send a emailmessage to, hrough a normal email client
Hi!
It's an error from the built in .NET e-mail library - it does not come from the Newsletter Studio code.
When you say "normal email client" do you mean that you can send using the SmtpClient-class in C# och something like Outlook or Gmail?
It might be that there is something wrong with your SMTP-configuration? Did you configure the server and does it pass the "Test connection"-test?
// m
Hi Markus.
Each day we send approx. 500 emails. Around 15-20 of them fail, and most of the failed emails have the listed error, so our configuration is functional ("Test connection" is OK).
With a "normal email client" i menat Outlook and gmail.
Hi!
Is it always the same addresses or does that differ?
The error comes from the .NET SmptClient-class which is out of control of the Newsletter Studio-package.
But you are sure that all these addresses works in other clients?
Are you able to send out "test emails" to these addresses?
The email adresses differ. Yes i'm able to send a test email to the adresses
Ontop of Markus's query, there may be a limit into SMTP server that is designed to prevent spam sendings.
It could be worth checking with them as the error you are referring to indicates that the .NET SMTP client is timing out during the send process when it is waiting for confirmation from the SMTP server itself.
In the past I've seen this error when too many individual emails have been sent to an SMTP relay that isn't designed for bulk distribution.
I agree.
@Jan - What is the total number of emails being sent out from the server?
We send out around 1K every day. We have a limit of 50 emails/second but we shouldn't hit the limit. We batch the emails in code and limit them to 10 per second.
Hi Jan,
Have you checked for any memory leaks from your code? Are you disposing of your objects correctly etc?
Can we see your code for sending the email?
Regards
Craig
We've had this with AWS. Basically EC2 instances are throttled when sending email on port 25.
https://aws.amazon.com/premiumsupport/knowledge-center/ec2-port-25-throttle/
So you will encounter sporadic SMTP delivery failures.
You have two options:
Use port 587 instead of 25 (if you can) - they don't throttle this port - see https://forums.aws.amazon.com/message.jspa?messageID=555499
Request an exception - https://aws-portal.amazon.com/gp/aws/html-forms-controller/contactus/ec2-email-limit-rdns-request
Hope this helps,
Jay
Thanks for helping out on this one Jay!
We are using port 587. I didn't know that they didn't throttle that port. Then I guess throttling isn't the problem.
Are you using SES? If so, its also worth double checking SES limits:
http://docs.aws.amazon.com/ses/latest/DeveloperGuide/manage-sending-limits.html
Good luck!
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