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Domain Throttling
Posted: Wed Aug 22, 2007 11:38 pm
by klang
Hi...
I've heard that we should not send the same newsletter to many reciepients of the same domain at one particular time or else emails might get rejected or considered a spam. Is it true?
I can write the script to limit this. My problem is I don't know the rules.
How many xxx emails per yyy (day/hour/minute) for one domain?
I've tried to search for this but had no luck. Anyone knows?
Thanks,
- Klang
Posted: Thu Aug 23, 2007 4:20 am
by Chris Corbyn
There are no rules. Server's will often have a limit of 100 envelopes per email, per connection. Basically that means don't send *the same email* to more than 100 recipients at a time. If you're using batchSend() this won't happen anyway because each email is unique to the recipient in question (it has a unique To: header).
How many emails are you sending on one connection. It seems like loads of people are trying to send 10-20K+ emails through a single connection which is slightly crazy really

Posted: Thu Aug 23, 2007 11:19 am
by klang
Thanks for a quick response.
My application need to send 50,000+ customized+trackable emails per a newsletter. I'm using cron to check the newsletter schedule and flag the database if it need to be sent. Another cron job to send 200 flaged items every minite (with Swift_Plugin_AntiFlood(100, 5))
I did the benchmark test and I can easily send 600 emails within a minute (from starting script to the last email out of Postfix). Very impressive indeed. The swiftmailer is rock.
I used Sendmail connection with Decorator, AntiFlood plugins, and a lot of database interaction in the process. I did not use batchSend() though. I just loop the $swift->send(...). Is it a downside of doing this?
I have a limited knowledge about mail server process. From what I describe above, how many email sent per one connection? I guess it was 100 emails/connection because of Antiflood, right?
Back to my main question, I do concern about sending too many emails to gmail, yahoo, and hotmail in a short period of time. I've heard that they have some limitations but I cannot find a general rule for this.
Any suggestion?
Thanks,
- Klang
Posted: Thu Aug 23, 2007 6:26 pm
by Chris Corbyn
klang wrote:I did the benchmark test and I can easily send 600 emails within a minute (from starting script to the last email out of Postfix). Very impressive indeed. The swiftmailer is rock.
Glad to hear it
klang wrote:I used Sendmail connection with Decorator, AntiFlood plugins, and a lot of database interaction in the process. I did not use batchSend() though. I just loop the $swift->send(...). Is it a downside of doing this?
Yes and no. Swift::send() throws exceptions if something goes wrong. in PHP5 they can be caught and dealt with via try/catch but in PHP4 it's not a fun experience dealing with the errors. batchSend() deals with errors and re-tries anything it cannot send up to a maximum number of times. But the basis of batchSend() is just send() inside a loop with a bit of extra code anyway
This may be of interest:
http://www.swiftmailer.org/wikidocs/v3/ ... _component
klang wrote:I have a limited knowledge about mail server process. From what I describe above, how many email sent per one connection? I guess it was 100 emails/connection because of Antiflood, right?
Yes, AntiFlood disconnects after the 100 emails you set, then it basically starts a fresh connection for the next 100 emails, and so on, and so on, and so on....
klang wrote:Back to my main question, I do concern about sending too many emails to gmail, yahoo, and hotmail in a short period of time. I've heard that they have some limitations but I cannot find a general rule for this.
I'd like to help you there but I really don't know. I've never heard about this but I don't know everything unfortunately so it's possible. I'd like to know if you do happen to fnd anything else out though

We use Swift to email a large userbase (20K+) but we batch at 100-per-connection and we've never had any issues

Posted: Fri Aug 24, 2007 2:28 am
by klang
I did find some info and wanted to share with you guys
Hotmail
http://postmaster.msn.com/Guidelines.aspx
Sender must not open more than 500 simultaneous connections to MSN Services inbound e-mail servers without making prior arrangements.
Yahoo
http://help.yahoo.com/l/us/yahoo/mail/y ... ostmaster/
While we have not published guidelines for numbers of connections you can concurrently use, we ask that you treat our resources with respect. The more you take, the fewer there are for others, which may force us to deprioritize your connections.
Gmail
http://mail.google.com/mail/help/bulk_mail.html
There is no information about simultaneous connections limitation for gmail.
Hope this help some people,
- Klang
Posted: Fri Aug 24, 2007 2:39 am
by klang
We use Swift to email a large userbase (20K+) but we batch at 100-per-connection and we've never had any issues
Glad to hear that. I'll use 100-per-connection as a rule in my application then.
Thanks for all your help,
- Klang