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[solved] Mailer Error: Could not instantiate mail function

PostPosted: 5:46pm, Fri 09 May, 2008
by thayerw
I'm posting this solution for anyone who might be searching the forums endlessly for an answer. Moderators, you might want to add this to the FAQ forum category.

The Problem:

Test emails work fine and so do small batches, but full lists (50+ users) report the following error in the eventlog shortly after queueing a batch:

Code: Select all
Mailer Error: Could not instantiate mail function

The Reason:

Bluehost limits email to 50 messages per hour by default. Once this limit has been exceeded, the above error is produced in the PHPlist eventlog after each individual message is sent. You can verify this by looking at your server error logs; it will likely state that the hourly email limit has been reached.

The Solution:

You've got two choices:

    Throttle your email below the acceptable limit (50/hour). Keep in mind that your regular email traffic must be considered as well. If you send 50 list messages per hour, you won't be able to send your normal email for another hour either.

    The other solution is to contact Bluehost and request that the limit be increased--there's no guarantee that they will, but it could be worth a try. Don't bother doing this if you are using PHPList to spam unsolicited messages--it will just get your account terminated.

Although my experience with this issue has been limited to Bluehost, there's no reason why this error wouldn't apply to other hosts. When in doubt, check your server's error logs for more details.


PostPosted: 6:23pm, Wed 14 May, 2008
by J_S
this is great, thanks

throttle by the minute

PostPosted: 2:14am, Wed 02 Jul, 2008
by hightwo
you can also set the throttle to throttle by the minute. (change 3600 seconds to 60 seconds)
this way you set it to send, say, 7 messages per minute. setting the page this way, allows the page to autoreload. if the delay is an hour, you are likely to be logged out.
also, bluehost was good about upping the limit for me. i have a 4000-member list. if i was limited to 50 messages per hour, it would take days to send messages.

Re: [solved] Mailer Error: Could not instantiate mail function

PostPosted: 7:28pm, Mon 12 Apr, 2010
by iasminb
I found that the solution for me was that the FROM email address had to match my domain. So it should be if my domain is

Re: [solved] Mailer Error: Could not instantiate mail function

PostPosted: 9:31pm, Mon 16 Aug, 2010
by tomsskyline
Thanks thayerw and hightwo ... I use Bluehost, too ... I called them and I discovered my hourly limit was set at 150; and they bumped it for me with no problem. :D