I have multiple programs that send email on a shared server with a relatively low email limit. These programs are completely separate and can each individually throttle mail but cannot do so in relation to the others. Currently, whenever the hourly limit is reached, our host just starts dropping the emails. They say they have no way to change this behavior and basically suggested that I ask around.
Does anyone know of any programs that will throttle email server wide on a shared server?
I'm fairly certain it is not possible to throttle emails across many different scripts/programs that you have described on a shared server. You will likely not have access to any shell on the server or the ability to install any additional software and therefore this is not an option.
Another option is if for example you have a limit of 500 emails per hour and you have two scripts requiring emails, set each individual limit to 250 so as to not go over the limit. This will make sending considerably slower but will ensure that no emails are dropped. (the numbers are all just for the example)
The best option however is to ask your host if they can change the email limit, change your plan or move to a VPS or dedicated server where this isn't a restriction.
This guy has come up with an interesting solution to this problem, he 's chaining to instances of postfix. http://www.void.gr/kargig/blog/2011/12/19/rate-limit-outgoing-emails-from-php-web-applications-using-postfix-and-policyd/
In your case, I 'm not sure if it can be done because it depends on the type of shared server. If you have command line access and can set up postfix on high ports, it should work fine. You could also shop around for servers where you have root access (vps) - they are cheap enough.
Your problem could get solved horizontally as well, since your outgoing mail needs seem to be relatively bounded. You could get a few cheap shared server accounts and have each of your programs use a different mail server.
