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Send thousands of emails at a time, traps / best way?

I am writing a C # tool (and System.Net.Mail) that will send about 4000 letters.

Is it possible to simply iterate over a list of 4000 email addresses and send an email one at a time? or can it cause any potential problems?

Is there a better way to do this?

thanks

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c # email email-spam
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5 answers

First of all, you should have an rDNS record that will return the IP address back to the domain name. Without it, mail services such as GMail will store your emails for hours or even days. In addition, you can be blacklisted after several dozen letters. rDNS can usually be set using the host control panel or at the request of support.

Secondly, do not be tempted to use the SMP servers of your Internet service provider or GMail. Your daily quota will end quickly. Usually it is not allowed to send more than a few dozen letters (50 for GMail AFAIK). So send mail from your server or use a third-party service, for example auth smtp .

Such services are also useful if you cannot install rDNS for any reason.

PS If the content of your letters is in order (that is, they are not really spam), and rDNS / SMTP are installed correctly, you can send them in any case without pauses.

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If you do not violate any restrictions on the server, such as memory or disk space, there is technically no problem. However, you will have problems with providers and mail forwarders who can block your domains for spam - right or wrong.

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You can send 4000 emails at a time, but you run the risk of being labeled very quickly as a spammer.

Your best option is to "send the package" to send maybe 100 at once, send another 100 in 10 minutes, etc.

If you do this this way, you are unlikely to be considered a spammer.

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Make sure that the machine sending the mail has a valid PTR record, that is, if you send from the site www.example.com with IP 1.2.3.4, a PTR request of 1.2.3.4 will return www.example.com; I looked at SPF and DKIM , too.

Some email hosts have an inbound speed limit (like Hotmail used in the past) - "if you send us more than x emails / minute, you get a higher spam score." I had a script to "move the queue", so the speed per minute for one server was reduced.

Also check this out: there are a lot of helpful tips on email content , but this is a bit off topic.

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In addition to what was mentioned above, be sure to set up an adequate log.

those. you must register sent emails, so if you need to resend emails, you can be sure that you should not send duplicates.

In addition, you can configure the application to register returned emails and use it to delete addresses, etc.

You can, of course, write your own software or buy it.

http://www.quiksoft.com/bouncebuster/

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