Re: [twsocket] Using lots of TSmtpCli in a single application
Also if a MX refuse you because of some blacklist then remove thoses mails from the queue and send you a mail alert so you can investigate why destination refused your mail. It's important not to fail an email on a first refusal, due to the wide usage of 'greylisting' where the SMTP server rejects the first email attempt and then allows a second attempt, typically 10 to 15 minutes later. Sometimes the response mentions greylisting, but some SMTP servers don't even do that. MAIL FROM: nursery...@englishmotorsports.com 250 OK nursery...@englishmotorsports.com Sender ok RCPT TO: i...@magsys.co.uk 451 Greylisted, please try again in 600 seconds Once an email has been sent successfully, the server adds the sender to an internal list so future email is not delayed. Greylisting is very successful in stopping spam, at least for the moment, it stops 500 to 1,000 spams a day here. However have a couple of Delphi applications that currently sent email without using a queue or a 15 minute delay, which really need updating to cope with greylisting. Angus -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
Hello Angus, I usually do it according to fail code 5.x.x or 4.x.x for 4.x.x I retry later, for 5.x.x I pout them appart to check manually why they have been rejected. regards. Also if a MX refuse you because of some blacklist then remove thoses mails from the queue and send you a mail alert so you can investigate why destination refused your mail. ARMSL It's important not to fail an email on a first refusal, due to the wide ARMSL usage of 'greylisting' where the SMTP server rejects the first email ARMSL attempt and then allows a second attempt, typically 10 to 15 minutes ARMSL later. Sometimes the response mentions greylisting, but some SMTP ARMSL servers don't even do that. ARMSL MAIL FROM: nursery...@englishmotorsports.com ARMSL 250 OK nursery...@englishmotorsports.com Sender ok ARMSL RCPT TO: i...@magsys.co.uk ARMSL 451 Greylisted, please try again in 600 seconds ARMSL Once an email has been sent successfully, the server adds the sender to ARMSL an internal list so future email is not delayed. ARMSL Greylisting is very successful in stopping spam, at least for the moment, ARMSL it stops 500 to 1,000 spams a day here. ARMSL However have a couple of Delphi applications that currently sent email ARMSL without using a queue or a 15 minute delay, which really need updating to ARMSL cope with greylisting. ARMSL Angus ARMSL -- ARMSL To unsubscribe or change your settings for TWSocket mailing list ARMSL please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket ARMSL Visit our website at http://www.overbyte.be -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
On Aug 16, 2009, at 14:43, Pete Williams wrote: Previously my app used a single TSmtpCli and this all worked fine. Now however I have to send mail on behalf of lots of accounts and the number of TsmtpCli components in use simultaneously, used in a multi threaded application, could be in excess of 100. I created a mail queue system using a customized TSmtpCli component (among other things) and, as far as I recall, I was sending 10,000 messages in a couple of minutes--all within a single thread. ICS Components are very good for this sort of thing, and you do not need multiple threads to use it. Since the components are asynchroneous, slow server connections or responses should not affect your performance when using multiple components simultaneously. The thing that may cause a delay is DNS look-up, which is an expensive operation, and typically blocks. Your description of the project does not seem unusual at all, and in fact, as others have said, 200 messages per hour seems rather low. You shouldn't have a problem using ICS for it. dZ. -- DZ-Jay [TeamICS] http://www.overbyte.be/eng/overbyte/teamics.html -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
On Aug 17, 2009, at 04:45, Dod wrote: I usually do it according to fail code 5.x.x or 4.x.x for 4.x.x I retry later, for 5.x.x I pout them appart to check manually why they have been rejected. This is the correct way of handling. As per the RFC, error codes win the 400 range are transient errors, meaning that they are temporary, and the sender should retry eventually; while codes in the 500 range are permanent errors. Of course, servers are not required to adhere to the RFC, but I haven't come across one that does not in this regard. It's for their own benefit, for they stand to break the entire system and lose e-mail if they send the wrong response. Greylisting and other anti-spam techniques should result in a 4.x.x error. Any mail sending application should be smart enough to re- queue these. 5.x.x errors must not be re-tried without modifications. In my mail queue server I have a simple algorithm to attempt to determine the reason for the failure, and sort them so that they can be manually analysed and corrected if necessary. The most common errors I've seen are: 1. User not found (account closed) 2. Destination server blacklisted in ORDB 3. Common typo in domain name (e.g. yaho.com, gmail.cmo, etc.) dZ. -- DZ-Jay [TeamICS] http://www.overbyte.be/eng/overbyte/teamics.html -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
Thanks for all the messages! Some useful things for me to know. My question wasn't about email volume as such, but simply about having lots of TSmtpCli components active at any one time, even if they are not doing anything. The application I'm working on is 9 years old, has many thousands of man hours spent on it, and whilst it would be nice to have a single TSmtpCli, in order to avoid a massive code rewrite it's much easier for me to have lots of TSnmpCli components, rather than one (you can't see it, but I can of course). Reading the responses, it looks like this is somewhat un-orthodox but will not generate any stability problems at all with respect to ICS - which is what I'd hoped. Thanks again, Pete _ Windows Live Messenger: Thanks for 10 great years—enjoy free winks and emoticons. http://clk.atdmt.com/UKM/go/157562755/direct/01/ -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
This is a really useful thing for me to know, thanks for posting this. This is the correct way of handling. As per the RFC, error codes win the 400 range are transient errors, meaning that they are temporary, and the sender should retry eventually; while codes in the 500 range are permanent errors. Of course, servers are not required to adhere to the RFC, but I haven't come across one that does not in this regard. It's for their own benefit, for they stand to break the entire system and lose e-mail if they send the wrong response. Greylisting and other anti-spam techniques should result in a 4.x.x error. Any mail sending application should be smart enough to re- queue these. 5.x.x errors must not be re-tried without modifications. In my mail queue server I have a simple algorithm to attempt to determine the reason for the failure, and sort them so that they can be manually analysed and corrected if necessary. The most common errors I've seen are: 1. User not found (account closed) 2. Destination server blacklisted in ORDB 3. Common typo in domain name (e.g. yaho.com, gmail.cmo, etc.) dZ. _ Windows Live Messenger: Happy 10-Year Anniversary—get free winks and emoticons. http://clk.atdmt.com/UKM/go/157562755/direct/01/ -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
The application I'm working on is 9 years old, has many thousands of man hours spent on it, and whilst it would be nice to have a single TSmtpCli, in order to avoid a massive code rewrite it's much easier for me to have lots of TSnmpCli components, rather than one (you can't see it, but I can of course). The issue we were discussing was not the use of a single TSmtpCli which is clearly unsuitable for all but the most simple mail servers, but whether you should be using threads with multiple TSmtpCli components (or most other ICS components for that matter). I have an application that captures data on 400 TWSockets simultaneously, in a single thread. As was said, two or more threads are beneficial where there are multiple processors available to the application and you can hog the entire server, or where you really are handling thousands of simultaneous connections. Angus -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
Hello Angus, You are true, I made a mistake talking about multiple threads, I meant multiple components in a single thread with a thread dedicated to the smtp component's so it is separated from the main GUI thread so the visual interface (if any) should be always responsive whenever the smtp thread is working hard. regards. The application I'm working on is 9 years old, has many thousands of man hours spent on it, and whilst it would be nice to have a single TSmtpCli, in order to avoid a massive code rewrite it's much easier for me to have lots of TSnmpCli components, rather than one (you can't see it, but I can of course). ARMSL The issue we were discussing was not the use of a single TSmtpCli which ARMSL is clearly unsuitable for all but the most simple mail servers, but ARMSL whether you should be using threads with multiple TSmtpCli components (or ARMSL most other ICS components for that matter). ARMSL I have an application that captures data on 400 TWSockets simultaneously, ARMSL in a single thread. ARMSL As was said, two or more threads are beneficial where there are multiple ARMSL processors available to the application and you can hog the entire server, ARMSL or where you really are handling thousands of simultaneous connections. ARMSL Angus ARMSL -- ARMSL To unsubscribe or change your settings for TWSocket mailing list ARMSL please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket ARMSL Visit our website at http://www.overbyte.be -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
[twsocket] Using lots of TSmtpCli in a single application
Hi I've used ICS components for a while now and had great results. I have something new to do and wanted some advice before starting a new project. Previously my app used a single TSmtpCli and this all worked fine. Now however I have to send mail on behalf of lots of accounts and the number of TsmtpCli components in use simultaneously, used in a multi threaded application, could be in excess of 100. Assuming that the machine has enough memory and processor power, am I likely to run into any problems? I don't evisage the email volumes being massive - say 20 per hour per account, meaning something like 200 per hour outgoing per application. My reason for asking is simple - I'm doing something unusual. If it is likely to be a problem I can try concentrating all emails through a single Tsmtpcli but because of the code base I am working with this will be much harder to do. Any comments welcome. Thanks in advance! _ Upgrade to Internet Explorer 8 Optimised for MSN. http://extras.uk.msn.com/internet-explorer-8/?ocid=T010MSN07A0716U -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
Hello Pete, 200 mails per hour is really not much, a single thread can do much more. But you may be slowed by the other side smtp server if it is slow or timeout. So doing multi-thread is a good way to maintain a good average speed. You can create 20 threads with a common queue that each thread can take mails from, so if a thread is slowed because of slow or timed-out smtp server, then the other threads continue to empty the queue and send e-mails to other smtp servers. In case you send multiple mails so same MX domain, then make some function that will re-arrange the queue to move slow or timed-out domains to the end of the queue so you'll retry them later. Also if a MX refuse you because of some blacklist then remove thoses mails from the queue and send you a mail alert so you can investigate why destination refused your mail. regards. PW Hi PW I've used ICS components for a while now and had great results. PW I have something new to do and wanted some advice before starting a new project. PW Previously my app used a single TSmtpCli and this all worked fine. Now however I have to send mail on behalf of lots of accounts and the number of TsmtpCli components in use simultaneously, used PW in a multi threaded application, could be in excess of 100. PW Assuming that the machine has enough memory and processor power, am I likely to run into any problems? PW I don't evisage the email volumes being massive - say 20 per hour per account, meaning something like 200 per hour outgoing per application. PW My reason for asking is simple - I'm doing something unusual. If it is likely to be a problem I can try concentrating all emails through a single Tsmtpcli but because of the code base I am PW working with this will be much harder to do. PW Any comments welcome. Thanks in advance! PW _ PW Upgrade to Internet Explorer 8 Optimised for MSN. PW http://extras.uk.msn.com/internet-explorer-8/?ocid=T010MSN07A0716U PW -- PW To unsubscribe or change your settings for TWSocket mailing list PW please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket PW Visit our website at http://www.overbyte.be -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Using lots of TSmtpCli in a single application
Pete Williams wrote: Hi I've used ICS components for a while now and had great results. I have something new to do and wanted some advice before starting a new project. Previously my app used a single TSmtpCli and this all worked fine. Now however I have to send mail on behalf of lots of accounts and the number of TsmtpCli components in use simultaneously, used in a multi threaded application, could be in excess of 100. 100 connections and more in one single thread is no problem. Anyway don't use one thread per connection, that was wasted resource! Since ICS works asynchronous there _basically is no need for multiple threads. However if you want your application scale well with multiple processors and keep your GUI responsive create as many additional threads as CPUs/cores are available and divide work/number of connections accordingly. -- Arno Garrels -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
