West Wind Internet and Client Tools
SMTP situation.
Gravatar is a globally recognized avatar based on your email address. SMTP situation.
  Denis Chassé
  Oct 26, 2022 @ 10:21am


I have to send a lot of emails. Sometimes the person doesn't receive the email she was supposed to receive.

I guess this happens for whatever reasons based on what happens on the internet at that precise moment.

With wwSMTP There is the property nTimeout

My question is, Should I increase that property length? or should I try sending several times the same email with a for next loop for example?

Gravatar is a globally recognized avatar based on your email address. re: SMTP situation.
  Rick Strahl
  Denis Chassé
  Oct 26, 2022 @ 08:14pm

Email is not a reliable protocol and has never been. When you send an email, you can only validate success of the process up to the mail server you are using to send to. The mail server might provide more information on whether the email was received on the receiving mail server, but even that can't verify on whether the email was delivered or more importantly not instantly filed as SPAM.

There are a million things that affect email delivery - if you're sending emails through a private server that you run yourself, you very likely are blacklisted which will automatically send email to SPAM folders in many email systems for example. Even if you use some sort of mail service, the service may have an issue with reused IP Addresses that might have been used for SPAM... and on and on and on. There are entire books written on how to make sure that email has a high success rate to reach its destination.

There are a number of things that help in htis regard:

  • Use a well-known, reputable mailnig service like Mailgun, SendGrid, Twilio etc.
    These services are your best shot at getting a server that is 'clean' and won't immediately be blacklisted. Sending emails through Gmail, or MS Live SMTP servers are very likely to get flagged.

  • Use a Receiving Mail service that has advanced Mail Spam Filtering
    The biggest culprit to emails not making it to their destination is usually due to custom or in-house email servers that don't have good Spam management. These types of services just look at black list and trash anything that is on these lists or use crude word check lists without further checking for relevant content or user associations etc.
    I realize you can't control that from your application, but that's the #1 culprit for non-delivered email in my experience.

  • Use a service and stick with it
    If you use a third party service build a good reputation for your email domain and IP address and keep with that. Don't switch around a lot as the reputation scores have to start over.

  • Make sure you have your Mail DNS configured properly
    Make sure your sending email domain has all the MX, SFP, DMARC entries set up to avoid your domain getting hijacked for junk mail. This is not easy to set up - I struggle with this every time, but there are tutorials online for this.

+++ Rick ---

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