I remember Eudora
I also remember why I (reluctantly) moved away from it.
1 Eudora had problems with IMAP. Eudora had _serious_ problems with IMAP. Around 2003 I started to set up new email accounts on IMAP servers; Eudora barfed, repeatedly, with several though not all of them. I could never figure out why some IMAP accounts worked perfectly but others emitted the magic smoke on contact. It was easier to just find a replacement email client.
2 Eudora had problems with UTF-8. Eudora pretended to be able to handle UTF-8, but really couldn't. This broke some mail. In particular it broke some mail from people who we had to work with and who used UTF-8 because they had to talk to people who didn't use the Latin alphabet and it was too much like work to rig their system to use two different charactersets, so all outgoing mail from them was UTF-8. Eudora would usually handle the posts, but on several occasions it broke spectacularly. There was a plug-in which handled UTF-8; it broke, too. Once again, it was easier to just find a replacement email client.
3 Qualcomm went off their meds. Instead of doing things like fixing the IMAP and UTF-8 problems, they did things like adding 'peppers' to tell users how 'hot' their posts were. My users started to compete to see how short they could make a post and still get three peppers, without using any profanity. The champ got three peppers with a post 11 words long and containing not even one 'objectionable' or 'inappropriate' word. Suggestive words, yes, but nothing actually profane. This 'feature' was amusing but useless. It was not the only such feature in Eudora, just the most spectacularly idiotic.
4 Qualcomm went further off their meds. They had the 'free' version, which was limited; they had the 'supported' version, which displayed ads in the lower left corner... and which screamed bloody murder if anything covered up the ad display. At this time there was a useful add-on for Macs which displayed a list of running apps; the default location was right where Eudora had the ads. Users thought that the add-on was a lot more important than Eudora. There was the 'full' version, licensed rentboy fashion, for a year. We noticed that new versions of Eudora tended to show up at 13-15 month intervals, so that the license would have run out and we'd have to pay again. It was cheaper and simpler to get a replacement email client.
5 Eudora supported encryption... if you were in the US. Export versions didn't have the encryption, and that remained so for some time after the Feds stopped saying that encryption software was a munition of war and requiring an arms dealer license to export it. On occasion our staff had to go outside of the US, with their laptops... and the munition of war installed on those laptops. We didn't feel like applying for an arms dealer license. We also didn't feel like installing the crippled export version. We particularly didn't feel like installing the crippled export version after the Feds (reluctantly) stopped saying that software was the equivalent of cruise missiles. Other people ignored the Feds. It was simpler to just get a replacement email client.