Email Users with S2 Member

There are a couple of questions we can start with to see which direction to go.

1. Have you used the DEBUG feature in Email Users to see what the mail headers Email Users constructs? If so, do they look correct? In your case, I would expect the BCC header to contain the list of email addresses you would expect to receive the message you are sending?
2. Have you checked with your hosting provider to see of there are any limitations on sending email? Many providers limit the number of recipients which you can email and one time and/or the number of email messages you can send in some period of time (e.g. 500 per hour).

If your hosting provider limits the number of recipients per email, you can fix that with the Max BCC setting. If your hosting provider has a limit on the number of emails per hour (or something similar) it may be harder, or in some cases, beyond Email Users ability, to solve.

Marking this as resolved for now.

What does the email log come from? Your hosting provider? There is no specific log that Email Users generates, the only confirmation you receive is the note at the top of the page which reports how many recipients were sent the email.

Once the email is dispatched, there is no additional information. The WordPress API function wp_mail() simply returns a true or false and as the documentation notes, a true doesn’t necessarily indicate success in the mail actually being send.

The functionality you are asking for already exists. The BCC limit setting will do exactly what your describe. If you have 1347 target recipients and set the BCC limit to 100, Email Users will send 14 emails, 13 emails will have 100 recipients and the 14th will have 47.

Now if your ISP restricts how many emails you can send per hour or day, that may be a problem as Email Users does not have an support for scheduling email delivery.

One of the things about having a very large BCC limit, or none at all, is you end up with very large header strings. It is possible that the string is getting truncated somewhere and it would be really hard to know exactly where.

I would do what you are doing: Keep trying successively smaller values until it works. The issue is the risk of annoying your subscriber base with potentially duplicate emails. I don’t have a good answer for this other than to create a slew of test users and test email addresses (Gmail supports this with the + operator in the email address).

I had created a small plugin to generate a bunch of dummy users for my Swim Team plugin at one point but it no longer works – I may have to dust it off and see if it would be useful for generating test users for Email Users.