Thunderbird Mail Stalling on outgoing

  • Thread starter Thread starter Richard John
  • Start date Start date
R

Richard John

When I send an outgoing email with an attachment of almost any size
(including only a screen shot) it will stall at about 50%.

The reason that I am mentioning it here is that it is happening only on
the two computers running Windows 7 (one 32 the other 64) My old desktop
running XP does not have this problem.

I have tried everything, including changing anti virus from Avast to
Microsoft Security Essentials - scanning and non scanning outbound mail
and with no change. Any ideas would be appreciated.
Richard
 
If you have tried everything, that means you have asked in the Thunderbird
newsgroup, correct?

: When I send an outgoing email with an attachment of almost any size
: (including only a screen shot) it will stall at about 50%.
:
: The reason that I am mentioning it here is that it is happening only on
: the two computers running Windows 7 (one 32 the other 64) My old desktop
: running XP does not have this problem.
:
: I have tried everything, including changing anti virus from Avast to
: Microsoft Security Essentials - scanning and non scanning outbound mail
: and with no change. Any ideas would be appreciated.
: Richard
 
If you have tried everything, that means you have asked in the Thunderbird
newsgroup, correct?
Click to expand...

And if you're gonna do that, you have to use Mozilla's servers or no one
will see your post.
 
Richard said:
When I send an outgoing email with an attachment of almost any size
(including only a screen shot) it will stall at about 50%.

The reason that I am mentioning it here is that it is happening only on
the two computers running Windows 7 (one 32 the other 64) My old desktop
running XP does not have this problem.

I have tried everything, including changing anti virus from Avast to
Microsoft Security Essentials - scanning and non scanning outbound mail
and with no change. Any ideas would be appreciated.
Richard
Click to expand...

When this happened to me, it was caused by the ISP.

If the ISP disables all ICMP protocol on their mail server,
the mail server ends up in a "black hole".

(See "PMTUD black holes" or "Path MTU discovery")
http://en.wikipedia.org/wiki/Black_hole_(networking)

http://en.wikipedia.org/wiki/Path_MTU_discovery

"Many network security devices block all ICMP messages for
security reasons, including the errors that are necessary
for PMTUD to work. This can result in connections that complete
the TCP three-way handshake correctly, but then hang when data
is transferred. This state is referred to as a "black hole connection".
"

My ISP was really sneaky. They changed their end, without
telling anyone. When I'd go to send email, it would jam up
like yours. They claimed it was "all my fault" and "would
I please change the MTU setting of my router" or the like.
When in fact, the reason they wanted me to change the
MTU, was because their mail server no longer properly
supported the protocols used to support differences in
MTU size. Only their mail server gave me problems, and
nothing else was broken (surfing worked fine).

Talk to the support at your ISP (the provider of your email
server), and see if they don't blame it on you :-)

Now, you claim it jams up when you send a large attachment.
As a test, compose an email message and send it to yourself.
Make the message really large, by copying a lot of text into
it. With any luck, you'll jam up, even without any attachment
added to the message. In my tests, I think I could send short
email messages to myself, but not long messages. Long ones
would jam when sent.

Paul
 
When this happened to me, it was caused by the ISP.

If the ISP disables all ICMP protocol on their mail server,
the mail server ends up in a "black hole".

(See "PMTUD black holes" or "Path MTU discovery")
http://en.wikipedia.org/wiki/Black_hole_(networking)

http://en.wikipedia.org/wiki/Path_MTU_discovery

"Many network security devices block all ICMP messages for
security reasons, including the errors that are necessary
for PMTUD to work. This can result in connections that complete
the TCP three-way handshake correctly, but then hang when data
is transferred. This state is referred to as a "black hole connection".
"

My ISP was really sneaky. They changed their end, without
telling anyone. When I'd go to send email, it would jam up
like yours. They claimed it was "all my fault" and "would
I please change the MTU setting of my router" or the like.
When in fact, the reason they wanted me to change the
MTU, was because their mail server no longer properly
supported the protocols used to support differences in
MTU size. Only their mail server gave me problems, and
nothing else was broken (surfing worked fine).

Talk to the support at your ISP (the provider of your email
server), and see if they don't blame it on you :-)

Now, you claim it jams up when you send a large attachment.
As a test, compose an email message and send it to yourself.
Make the message really large, by copying a lot of text into
it. With any luck, you'll jam up, even without any attachment
added to the message. In my tests, I think I could send short
email messages to myself, but not long messages. Long ones
would jam when sent.

Paul
Click to expand...
Thanks Paul
I sent your message to my ISP since it is all greek to me
Richard
 
Daave said:
If so, why don't the e-mails stall when he uses the third PC (the one
running XP)?
Click to expand...

That would depend on the MTU setting of each computer. Perhaps
there is a policy difference between the OSes ? Or, perhaps the
user has already made a change purely by accident (while
"tweaking" the network performance).

In any case, if phoning the ISP gets an immediate response from
the support staff, then they probably know they've changed something
at their end to cause it in the first place.

The OP can always set up a second email client, and do the same
tests, and see if it "stalls" exactly the same way.

Paul
 
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