Not all the bcc email recipients receive their email.
Is there a limit on the number of recipients that can be sent an email at the same time? I know it is not my server as this is limited to 150 and I have no more than 50-60 in each group that I send.
Alla svar (5)
Yes, but if you add them all explicitly to the addressing box I'd expect you to get an error when you exceed Thunderbird's limit.
http://kb.mozillazine.org/Limits_(Thunderbird)#E-mail_addresses
As it mentions there, if you use a Mailing List you can get round this particular limit.
I am using the mailing list option. I don't receive any errors just complaints from people asking why they are no longer receiving my weekly emails.
Ouch!
have you considered a mail merge? There you send an individual and personalized message to each correspondent. It might be easier to unravel which ones are giving trouble.
I have an order form embedded into my emails that my customers fill out, so I'm not sure how a mail merge would work?
You create a template message with optional placeholders for the addressee's name etc.
No reason why this couldn't be your regular email message, I think.