Jeremy:
Gmail certainly does ignore dots in the left-side of an email address, but ONLY on left-sides of email addresses arriving into the gmail domain. firstsecond@gmail,com is treated the same as first.second@... and indeed the same as first....sec.ond..@.... This is quite legal. If there was already a gmail user with the name firstsecond and someone else tried to join gmail with the name first.second they would be told there was already a user with that name and to choose something different.
I have discovered recently that first+anytext@... is treated as first@... so gmail are truncating left-sides at the + sign. This at first looks like the same bug that we are discussing here, but it isn't - this is gmail's own private interpretation of left-sides of emails inbound to ITS OWN domain, NOT truncation of left-sides which are en-route to OTHER domains - a practice which is outlawed by RFC2821.
This means that groups.io need not be frightened of dots in the left-sides of email addresses in their own domain which are to be interpeted in some clever way when they arrive at groups.io. The fact that dots on the left side are commonplace and seem to be handled correctly by all known en-route hosts, means that if groups.io changed the + to a dot, it would certainly be handled correctly.
The problem I have raised in this thread is that there seem to be en-route hosts that DO truncate left-sides at the first + character in EN-ROUTE EMAILS, we have spotted one such en-route host that does this (either btinternet.com or synchronoss.net - we don't know which), and I think there must surely be others we haven't seen yet, since these people all buy their hardware/software from the same places. OK, the correct solution is to fix the hosts that do it, but I would make a case for implementing ANY solution which eliminates the problem NOW.
Regards
Peter
