West Wind Internet and Client Tools
Intermittent Failure to Mail Messages
Gravatar is a globally recognized avatar based on your email address. Intermittent Failure to Mail Messages
  MarshalR
  All
  Oct 22, 2021 @ 02:08pm

In the past week one of my clients using a VFP app which sends e-mails via WW Internet & Client Tools has started to experience intermittent Failure sending mail Error Messages. Sometimes E-Mails will go out numerous times successfully, followed by a series of Failure sending mail Error Messages followed by hit or miss successful sends.

The SMTP Server is: smtp.office365.com:587

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  Rick Strahl
  MarshalR
  Oct 22, 2021 @ 02:36pm

Most likely hitting quota limits with office365. Depending on your plan you likely have a limited number of messages you can send per hour (or whatever).

If you're doing bulk mailing, using a generic provider like Office365 or GMail really is not an option.

+++ Rick ---

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  MarshalR
  Rick Strahl
  Oct 22, 2021 @ 02:49pm

Thanks for your reply Rick

Not sending bulk mail How do I determine quota parameters?

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  Rick Strahl
  MarshalR
  Oct 22, 2021 @ 02:59pm

Not sure. Look in the Office 365 service agreements.

There's probably also some way to look at the logs to see what goes wrong. Also check the full error message you get back from the send message...

Given intermittent behavior I would fully expect the SMTP server refusing to send messages - if it works once - unless you're passing invalid information on certain requests - it should always work from the client perspective.

+++ Rick ---

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  MarshalR
  Rick Strahl
  Oct 22, 2021 @ 06:45pm

Normally I would get an SMPT Error Message with a number. In this case all I'm seeing is Failure sending email with no number.

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  Rick Strahl
  MarshalR
  Oct 23, 2021 @ 11:03am

That sounds like a connection error, server refusing the connection. The error info comes from .NET and wwSmtp just forwards what's available.

Make sure you're using a recent version as there has been an update that provides more error information in the latest update (7.23). It may provide more detail than that Failure to send error.

+++ Rick ---

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  MarshalR
  Rick Strahl
  Oct 24, 2021 @ 09:24am

OK - will recompile my test program with version 7.23 and see if more detail is available.

Marshal

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  Tom
  MarshalR
  Oct 25, 2021 @ 12:51pm

It appears that something has changed with Office365 smtp email. We have a number of clients that are using the smtp server: smtp.office365.com:587. We are getting more and more reports of intermittent failures 'Failure sending email'. It seems that the intermittency is becoming more failures than successes. Is anyone aware of what may be the root of the issue? Or a fix? T

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  MarshalR
  Rick Strahl
  Oct 25, 2021 @ 02:15pm

I recompiled my VFP App with Version 7.23 (Previously was running 6.15) and issue seems to have gone away for now - will be monitoring the situation.

Is it possible one of the bug fixes in 7.23 or previous 7.xx Versions could have also fixed this issue?

Also: Did Version 7.23 or previous 7.xx Versions automatically use TLS 1.2?

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  MarshalR
  Tom
  Oct 25, 2021 @ 02:17pm

Hi Tom,

The jury is still out but re-compiling my VFP App with Version 7.23 seems to have fixed the issue. Waiting to hear back from Rick (see the previous Post).

Marshal

Gravatar is a globally recognized avatar based on your email address. re: Intermittent Failure to Mail Messages
  Rick Strahl
  MarshalR
  Oct 26, 2021 @ 01:17pm

v7 uses TLS 1.2 by default. Older versions were using the defaults which would have been OS specific with Windows 10 getting TLS automatically, anything else only if the OS had enabled explicit TLS 1.2 support. I don't think that was your problem though because that's all or nothing. It either works or it doesn't.

The tools are updated regularly so it's possible some minor change helped with your issue, but I doubt it - the intermittent behavior seems to suggest it had to do with the O365 server limits. You'll find if or when you get another error and can look at the error message.

+++ Rick ---

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