Re: [fetchmail-users] reasonable poll intervals

[Uli Z. <ul...@ri...>]

Am 12.07.2006 um 08:05 schrieb Matthias Andree:

> And I even considered warning of deamon intervals shorter than 5  
> minutes. In fact, with many sites, polling in shorter intervals  
> just earns you a lockout.

I know this behavior from the pop mail server of my university.  
However, the critical interval that triggers a lockout after a few  
trials is 10 seconds (which sounds reasonable to me).

> And it's not like a polling interval of 5, 10 or 15 minutes made a  
> real difference.

I've never heard of that. Just as a comparison, Mac OS X's Mail  
application lets you choose polling intervals just in fixed steps via  
a pop-up. The available intervals are 1, 5, 15, 30 and 60 minutes,  
with 5 minute the default value. Judging from the respective  
discussion groups and personal experience, however, many Mac users  
switch the pop-up to 1 minute. Again, I never heard anyone complain  
that his wouldn't work.

> Trying short poll intervals with "keep" doesn't work too well either.

What could possibly go wrong?

> In fact, SMTP and UUCP don't require fetchmail at all.

Of course - but they require a specific server setup. I suppose most  
if not all ISPs would rather take care that their mail servers can  
handle short polling intervals of their customers, than offer an  
alternative SMTP solution which adds a lot of complexity for them.  
Complexity is more expensive than faster hardware.

Also, this would only be reasonably easy to configure if the client  
machine had a fixed IP address. Not even one common fixed IP for a  
local network (via NAT) would work as soon as more than one machine  
in the local networks wanted to receive its specific mails. Yes, you  
could differentiate the machines by private SMTP ports and respective  
NAT translation, but this gets all too complex for a general purpose  
setup. And note that even if IPv6 was already standard, and you could  
easily get as many IPs of your own as you wanted, many people would  
still prefer an NAT solution for their local network because of  
security reasons.

Besides, an SMTP solution has its disadvantages if you want to switch  
between receiving your mail at home/work and with a laptop on the  
road (where POP/IMAP are the only sensible solutions if you still  
want all your mails on your desktop machine in the end).

I have my own mail server that I can set up any way I want, and I  
considered using SMTP, but found POP with short polling intervals  
much more practical in the end.

Of course, the ideal solution technically would be a mail server that  
delivers mail directly via SMTP as long as this works, and  
immediately switches to POP when the recipient's computer isn't  
connected to the network anymore. If the recipient connects its  
machine to the network again, it should fetch all mails from the POP  
account that arrived while she/he was disconnected, and then send a  
special command to the server that tells it to switch to direct SMTP  
delivery again. (This last step would be necessary because it could  
be that the mails where fetched from a laptop on the road, in which  
case you wouldn't want to resume SMTP delivery to your desktop  
machine afterwards.) But as long as there aren't any pre-configured  
software solutions for the server and the client side, I doubt that  
such a complex solution will ever happen.

"Brute-force fetchmailing" ;-)) is just so much easier ...

             Bye
                     Uli
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