Pegasus Mail & Mercury

When sending, it takes a couple of minutes before the sedn fails displaying the following on-screen error message:

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>> 0025 250-ENHANCEDSTATUSCODES
>> 0016 250-PIPELINING
>> 0014 250-8BITMIME
>> 0019 250-SIZE 31457280
>> 0009 250-DSN
>> 0022 250-AUTH PLAIN LOGIN
>> 0015 250-DELIVERBY
>> 0010 250 HELP
<< 0012 AUTH LOGIN
>> 0018 334 VXNlcm5hbWU6
<< 0038 aXNhYWMuaGVpbnJpY2hAY2FyZG9uZXQubmV0
>> 0018 334 UGFzc3dvcmQ6
<< 0010 c29ueQ==
>> 0028 235 2.0.0 OK Authenticated
<< 0044 MAIL FROM:<**my email address**> SIZE=4510
>> 0047 250 2.1.0 <**my email address**>... Sender ok
<< 0026 RCPT TO:<***recipient email address**>
>> 0044 250 2.1.5 <***recipient email address**>... Recipient ok
<< 0006 DATA
>> 0050 354 Enter mail, end with "." on a line by itself
8: Socket read timeout.

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This is followed by this rejection message in the New Mail Folder: 

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..also, I wouldn't mind trying a beta version of 4.51, if it was possible to get a copy.

It would help a lot if you were to use the session logging so we can see all of the transactions and times up to the point of failure

>> 0028 235 2.0.0 OK Authenticated
<< 0044 MAIL FROM:<**my email address**> SIZE=4510
>> 0047 250 2.1.0 <**my email address**>... Sender ok
<< 0026 RCPT TO:<***recipient email address**>
>> 0044 250 2.1.5 <***recipient email address**>... Recipient ok
<< 0006 DATA
>> 0050 354 Enter mail, end with "." on a line by itself
8: Socket read timeout.

Hard to say if this a a simple timeout  or a packet fragmentation problem.  I would first increase the SMTP timeout to something like 120 seconds and if this did not help I would check for packet fragmentation.  The POP3/SMTP transmissions may fail if the MTU packet size is so large that a packet is fragmented.  In many cases the receiving system router blocks the receiving servers "packets fragmented" response to the sending system using "MTU Discovery".  These oversize packets are not accepted and so are resent.  This results in a timeout, generally at the end of the message transmission but it can be anywhere in the process.  You need to reduce the MTU size. Windows defaults to a 1500 MTU and many routers and DSL connections need 1492.  You might simply want to turn off the MTU Discovery operation.

You might want to get a copy of SG TCP Optimizer that I find quite handy.  http://www.speedguide.net/downloads.php  This little utility will allow you to test your MTU for maximum size without fragmentation against specific servers.  If will also make it easy to adjust the MTU. 

And finally, does this computer, by chance, happen to have an NVidia NForce 4 chipset on the motherboard?  If so, many other have had this exact problem, and it turned out to be an optimization setting for the built in NIC which caused the problems with packet fragmentation. Disabling the advanced optimization capability called "checksum offload" made all the problems of sending SMTP mail via WinPMail disappear.

Thanks for that.

Playing around with the MTU settings helped a bit, but did not fix the problem altogether... I disabled MTU discovery, and also checked that the MTU on the Interface is the same as on the ADSL Router (1492), then enabled it again... no luck. Anyway, these are my current settings:

These seem to work best, though it is still timing-up now and then. I believe this is a specific issue for Vista SP1, since it happened on both my home PCs and my office PCs after installing sp1 on then, so hopefully as more people out there get Vista SP1 someone will eventually find the answer...

..or perhaps v4.51 will fix it.