SMTP and Sending Limits for One Communications

EQ Admin

EQ Forum Admin
Staff member
One Communications allows email clients to make UP TO 500 SMTP connections from an individual IP address to per hour and 99 receipients per email message. If an IP makes more than 500 SMTP connections to the IP address will land on the DENIED " Too many connections received this hour from <IP address> " listing. At that point, any further connections attempts to SEND email thru will result in the following error:

451 - Too many connections received this hour from <IP address>

If a client does not make an SMTP connection to our servers for one solid hour they are automatically removed from this automated deny listing.

How did my IP address end up getting listed for too many SMTP connections this hour? 99% of the time this is due to a mis-configuration of the clients internal mail server owned and maintained by the client, OR this is due to a virus/trojan, or "open relay" type problem, also internal to the client's LAN.

  • Are you attempting to relay or send a BULK Mailing?
    • If so you should be using OR be sure you are using your own email server to relay email OUT to the WWW using DNS resolution
  • Are you running your own email server on your LAN? (i.e. Microsoft Exchange Server, SendMail Server or any other email server to send mail OUT to the WWW via SMTP)
    • If YES check to ensure you have your email server set up to "use DNS resolution to send outbound mail via SMTP" and NOT a "smart host"
    • If you have your own mail server "in-House" in order to send mail OUTBOUND to the WWW, you should not be using as a "smart host"
  • If you do not have your own outbound email server "In-House" and you rely strictly on to send mail OUT to the WWW, you may have been comprised by a SPAM virus or trojan of some sort, or your IP address may compromised as an "OPEN RELAY"
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