[MlMt] Mailmate r5874 Issue with accounts [Yahoo Server fails to stay online when laptop moves to a new internet connection]

[Bill Cole]

On 2022-03-07 at 08:04:25 UTC-0500 (Mon, 7 Mar 2022 13:04:25 +0000)
Henry Seiden <mailmate at lists.freron.com>
is rumored to have said:

> Hello,
>
> Just letting you know of continuing issue with Accounts staying on 
> line, in particular Yahoo! Coming back with an A1 connection error.

This is mostly a problem with Yahoo because of their low simultaneous 
connection limit but it is theoretically possible anywhere under the 
wrong conditions.

> I found that do duplicate the issue regularly in this version, and I 
> think later revisions as well of MailMate here are the steps:
> 1. Starting with a working, non-failing condition of MailMate, select 
> a different connection method. For instance without leaving my house, 
> I chose to go from a LAN connection (plugged in LAN cable) to wireless 
> connection (unplug the LAN cable and turn on the Wireless on the same 
> machine).
> 2. MailMate was left open on the desktop.
> 3. Immediately (within 30 seconds of changing connection methods the 
> warning popped up that the connection to Yahoo! Server had failed due 
> to the error and a choice of try later or take the account off-line 
> was required.

This is almost certainly unavoidable with certain network architectures. 
It is likely to be generally impossible to sustain any TCP sessions 
across that network change unless you've designed the network to not 
break sessions. To do that, you need to make whatever is doing your WAN 
link (and presumably NAT) see your machine on the new link as the same 
machine that just vanished on the wire. If you are using a single 
machine (e.g. SOHO router/WAP) for wireless and wired connections, it 
will never see a new wireless client as the owner of the NAT mappings 
that it has for the wired connection.


> 4. Disconnecting the account (taking it off line) got rid of the 
> warning.
> 5. Leaving it off for over 30 seconds, then turning it back to online 
> did NOT solve the problem. However, closing MailMate app for about a 
> minute and then restarting did solve the problem permanently, until 
> the next move to another wired or wireless connection.

That is 100% consistent with your router discarding the old NAT mappin 
gs before they've closed properly, and Yahoo taking a formally correct 
period to time out the session(s) using your simultaneous connection 
slots.

I've simply given up on using Yahoo for always-on IMAP: I check mail 
there manually only, not on a schedule, so MM doesn't always have a 
connection open. Obviously that's not an option if your Yahoo account is 
for serious use. (Mine is purely a testing tool.)


-- 
Bill Cole
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire