Can't send large attachments

Ernie - Thanks again for the reply. I checked the diagnostic page you recommended. I don't have wireless or ethernet...I'm in the sticks, and only have dial-up. (It took quit a while getting the 10.5.2 upgrade...but it did!). Is there a similar diagnostic I can us with dial-up? I'm using the Apple external modem. Also, please note that I can send attachments with no problem using Netzero as my SMTP server by restarting on my 10.4.10 partition and running Mail under Tiger. Mail works for me on Tiger...not on Leopard. Thunderbird works for me on Tiger...not on Leopard. Thanks again for taking the time with this.

Regards, Bill

Bill,

I cannot find what to recommend with dial-up. However, I see lot's of hits for software, etc to speed up dial-up modems and Netzero. You don't have anything like that, do you?

Ernie

Ernie - I just have standard Netzero install, which works fine on Tiger...with or without attachments. As a matter of fact, Netzero doesn't offer their "high-speed" service for Mac. I guess that iMac007 is implying, perhaps, at another post that you have participated in, that Apple knows something is wrong, and is working on it. Have you heard anything of this?
http://discussions.apple.com/message.jspa?messageID=6647530#6647530
Thanks again,Bill

Ernie - I failed to mention in my last post that I've installed Eudora on Leopard....it will allow me to send text, but no attachments......I guess I'll put it on my Tiger partition later on to see what happens.....Will keep you posted.

Bill,

I didn't really try to guess the meaning that analogy. I think Apple knew there were connection issues, and the update to 10.5.2 addressed those. I have no knowledge of further suspicions that Mail engineering might have in this regard.

The Mac I use Leopard on -- a Mac Pro -- has no internal modems. They are not an option, to my knowledge, from Apple. Were I to need dial-up, I would have to attach one via USB.

Ernie

PJ - Have you fixed your problem? Regards, Bill

Hi again PJ,

I would think what might be temporary about this "fix" is how the MTU was adjusted. If an entire LAN is powered down, and then everything turned back on the sequence the ISP suggests, then discovery of the proper MTU for proper uploading should take place someplace between the modem, router, and computers connected to the router -- if no router, should be easier. Computers (and applications) are now common that will communicate in a network at much faster and robust speeds than what can be achieved when going outside the LAN. This is why the balancing must take place, so that the connection is not overwhelmed during any upload.

Verizon was once famous when using Linksys routers to need MTU of 1492, rather than the 1500 default. Linksys used to have a special support document about how to change the MTU in the routers, so that all computers on the router will work. MTU of 1492 vs 1500 seems like a small difference, but it was (may still be but no confirmation) a critical difference.

The support document that I often link to here is for troubleshooting, and not the permanent fix. The longer term fix should depend on communication between the ISP and the user, and perhaps the manufacturer of devices used in the LAN.

See:

http://www.dslreports.com/faq/695

http://help.expedient.com/broadband/mtu.shtml

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

and

http://wiki.wireshark.org/MTU

Unfortunately much of what is written about MTU is oriented towards Windows, rather than OSX and Macs.

The need to "fix" the MTU arises only when the computer pushes the packet size and connection speed beyond what is optimum. This may be triggered by a new application, OS, modem, computer or other hardware.

What devices are in your LAN and connection to the internet?

Ernie

PJ,

In addition, let me review: the only problem I have ever had with sending via any SMTP in Leopard was a sluggishness in connecting before beginning uploading content. In my case, this long delay in connecting never resulted in any timing out or failure to deliver. My issue, as I have posted elsewhere, was solved (unwittingly) when a tech with my ISP, chasing a completely different issue (turned out to be on their end) had me enter primary and secondary DNS addresses in my modem (their modem, actually), rather than have that take place automatically as is the normal default situation.

As long as you are in contact with a tech from your ISP, it might be worth asking him/her to try that in your situation. It could be that would eliminate a cause of timing out, if that is a fair description of your issue.

Ernie

When you say you configured your settings with the DNS addresses, are they seen in the modem when you access it, as opposed to in System Preferences/Network?

Ernie

The ISP tech should be able to give you an address you can enter into your browser, and the pages that will show what is in the modem. The address may be on the order of 192.168.xxx.xxx. That will then require the entry of an Username and Password, which often are the defaults of admin & admin. This is something you should only do while you have the tech on the phone, probably. If like mine is now set, then Dynamic DNS will be disabled, and the screen in Setup for DHCP Configuration will contain the DNS addresses he has given you.

Ernie