No, we do not impose any specific sending rate limits, but we do monitor our servers for abuse, bottlenecking and other potential performance issues. If we find your sending activity is bogging down a server we may intervene and contact you or temporarily suspend your services.

We do impose a limit on the number of concurrent SMTP connections, however, which is set to 25 simultaneous SMTP connections per user. Use of a few sustained concurrent SMTP connections can help speed up the sending process, but use of many sustained SMTP connections in an attempt to send as fast as possible is not recommended and will actually significantly slow performance. This limit is designed to allow temporary SMTP connection spikes, not for sustained sending activity through lots of simultaneous connections.

Clients on dedicated High Volume servers do not have specific SMTP connection limits.

Our services require authentication, so unauthenticated sending is prohibited.

Yes, this feature is available by simply sending through a 6,xxx range port, either 6025 for standard SMTP or 6465 for secure SMTP over SSL. There is no additional charge for this service.

LuxSci does not use load-balanced sending to distribute email among multiple IPs.

We do not offer multiple IP addresses for bulk sending in our shared and dedicated environments. At LuxSci, IP addresses are obtained only in conjunction with SSL certificates to be used for a variety of reasons.

Yes, LuxSci does allow concurrent (simultaneous) SMTP connections so that you can do bulk sending in parallel streams for faster mail processing and sending. Accounts on our shared High Volume servers have a limit of 25 concurrent connections, and our dedicated High Volume servers have no specific connection limit, only what the hardware can handle. Using multiple concurrent connections for optimal sending performance works best when you have a few (3-5 in shared; 10-20 in dedicated) connections set for sustained sending--the high limit of 25 connections is to allow for temporary connection spikes.

Yes! LuxSci offers support for VERP to help in your bounced message analysis. For more details, please read our FYI Blog article VERP now supported for High Volume Bounce Analysis.

Yes! LuxSci supports DKIM for both inbound and outbound email flow. For more details, please see our FYI Blog article "DKIM: Fight Spam and Forged Email by Signing your Messages". DKIM is an enhanced protocol that evolved from the original DomainKeys protocol developed by Yahoo!.