For four months now I’m volunteering my time at Uniwersytet Dzieci organization (a child university). Amongs the others I’m helping in running lessons about the Blender software. Lessons are crowned with a show, where students can present their new skills. After organizing students mailing list I’ve encountered some problems.

The problem

I’ve gathered more than 40 emails to write to students about their roles in the show. I’ve created a couple of mailing lists, e.g. the list including all of the students. First mail was composed by adding this list as BCC to make addresses private. On the last lesson I’ve realized, that Gmail users had not received my mail, while students with addresses from other domains did.

The reason is unknown, but I’ve searched the web and have found some clues:

  • filters can reject mails, where receiver is in BCC
  • filters can reject mails if there is a big number of receivers
  • filters can reject mails if the server had received a big amount of messages from one address in a short period of time

I’m not completely sure if above statements are true (it was a quick search throught the forums), but none the less, Gmail was rejecting my mass messages, while individual written mails were delievered.

The solution

Thunderbird Mail Merge add on.

I’m composing mails from mailing lists as always, but instead messages are sent:

  • individually (just like I would send mails one by one)
  • in a 10 seconds intervals

I don’t know if this solves a problem, but I’m sure that there is no more I can do to avoid spam filters. Because in the end: Mail Merge is doing the same job, as if I would compose 40 emails one by one.