Email clients that don't accept HTML

I know you aren’t meant to send an HTML email without sending a plain text alternative, as “some email programs don’t accept HTML”. But which ones? I haven’t actually come across one (so far as I know). I keep stressing the importance to clients of sending a plain text version of their emails, but I’m starting to wonder why.

Lotus Notes (2006 release, and possibly others) doesn’t seem to, as emails I get from people using it are always plain-text. Some webmail services such as are plain text only. I’m sure there are some mobile phones that have native email clients that are plain text only as well.

Thanks Stevie. Interesting to know. I was starting to wonder if it was relevant any more.

The only time i ever see HTML emails these days is either when it’s a full out sparkling newsletter from Smashing Mag or someone else like them or when it’s a proper campaign by a company, at work i build them all the time but when it comes to building emails at home i simply just use plain text and some inline styling sometimes to get a nicer font but apart from that i just don’t see any reason why a user should have to wait for a server to send images to the client when he/she can just simply start reading why they got the email.

Sure. I do this for companies with CampaignMonitor. But they recommend you send a plain text version of these emails … hence the question of who (if anyone) sees the plain text version.