Do you impose any sending rate-limits? What about throttling SMTP connections, or impose hourly or daily sending limits?
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.
Can I send unlimited messages?
Are any major email providers overly sensitive to bulk email and thus may block your legitimate email?
Yes, we have found in particular that Yahoo!, gmail, and AOL seem more sensitive to bulk email than other providers. When sending to these domains we recommend limiting the rate and number of addresses you send to at each domain so you do not bombard them at once and end up blocked.
Can you do unauthenticated sending with LuxSci High Volume?
Our services require authentication, so unauthenticated sending is prohibited.