In "Tools -> Message Filters", find out which filter deletes her email,
and remove that filter.
If you don't find such a filter, then maybe her mail is being labelled
as spam. If Thunderbird does it, create a new filter to "Set Junk Status
to Not Junk" for email coming from her.
Mail can also get blocked before it ever gets to your computer: some
ISPs have set up "spam filters" which "drop on the floor" what they
think is spam, instead of transmitting it to the addressee. Alas, such
filters are not perfect, and both false negatives (spam not detected as
such, which gets transmitted, and which the addressee receives) and
false positives (legitimate mail erroneously detected as being spam) can
happen.
If possible, log in to your mail server and find out which settings are
set "at their end", so to speak. If spam filters are set, you may want
to disable them (and use Thunderbird's Junk Mail Controls instead).
If none of the above works for you, try to find a mail server where
spam, instead of being dropped, is simply diverted away from your inbox,
at some place where you can still access it, and, if appropriate, mark
some email as non-spam. (Gmail is one such mail server; I'm sure there
are others.) Then tell your friend to use that new email address.
(Thunderbird will let you get mail from any number of mail servers, so
you can keep your "old" email account together with the "new" one, and
get mail from both at the same time.)
Best regards,
Tony.
--
Hackers do it with all sorts of characters.
If you still don't get your friend's (future) mail (and know by other
means, such as a phone call, that she did send it), then the block may
be upstream, in which case the rest of my previous answer applies.
Note: I'm no Mozilla employee, I'm just a plain user like you. Next
time, please reply on the newsgroup (or mailing list), not by private
mail. You'll have more chances of a quick and full answer.
Best regards,
Tony.
--
Maternity pay? Now every Tom, Dick and Harry will get pregnant.
-- Malcolm Smith
If there isn't one next to yout Inbox, Sent, etc., then either you
haven't enabled Junk Mail Controls (in your Account Settings) or
Thunderbird hasn't yet found anything in your incoming mail that looked
like spam. In both cases, and since there was no mail filter against
your friend, the block is probably upstream, at your mail server's.
Check my first reply about how to proceed then.
Best regards,
Tony.
--
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SIR LAUNCELOT runs him through, grabs his spear and stabs the other
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"Monty Python and the Holy Grail" PYTHON (MONTY)
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