What would you like Mail.app to do that you're accustomed to with Eudora?
I'm using Lion's Mail and you can customize the toolbar by using the View menu -> Customize Toolbar. It may be the same for Snow Leopard.
Yes! Thank you, I was looking in the prefs.
Eudora is very keyboard-centric (plus I got my start in DOS). I feel I click way too much in Mail.
MailHub lets you do one-click filing which appeals to me.
I am not sure how to search globally. In Eudora I could search one box, a few boxes or all boxes quite easily. It seems like the search box in Mail will only search the box you are currently clicked on. I did read somewhere that it works if it's "set up right" but I haven't yet figured out how to do that (nor have I spent too much time doing so).
Eudora also allowed you to search on labels (ie flags). Not sure if Mail will allow that. One of the add-ons allows for different colored flags which is great, but I can pass that by. I'd really like to search across a group of boxes by flags though.
Huge thing Eudora did - was the option-click to highlight a group of messages, be it by date, author or subject. I will often let a thread build up in my mailbox for a week or so and when it seems to have petered out, I'll opt-click that last message and they all get highlighted and I file them. I was hoping MailHub would offer something similar or that the one-click filing would help me in that one.
The other Mail thing that really bugs me (and it looks like a plug-in will work at least one way, not sure if it will do both) is its insistence on embedded attachments. I'd much rather have attached attachments.
The more I use it the more I will find things I'm sure. I'm adapting best I can but I am definitely more productive in Eudora still!
Thanks

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I used Eudora since 1997 and I faced the same situation as you when I purchased an MBP last summer.
I've tried them all: Mail, Thunderbird, Postbox... I even spent $20 on MailForge over two years ago but I have given up on a fully functional version ever seeing the light of day.
The Mail plugins like MailHub didn't do much to improve the app IMO.
I have been using GyazMail for a number of months. And I am happy to report that I don't miss Eudora one bit. In fact, I wish that I had switched sooner.
GyazMail costs $18. Download the demo at
http://gyazsquare.com/gyazmail/. Here is a review:
http://email.about.com/od/macemailclients/fr/Gyazmail-Review-Mac-Email-Program.htm.
Hi MoJo! Gyaz and MF were the other two contenders. MF is pretty much out of the running especially based on the past two weeks promised updates. The fact I could never get it to download email kind of killed it was well! I tried 3 different accounts and none would work. The other huge annoyance was that I tried to sign up for the forum weeks ago to get help on my import and retrieval issues. Apparently you have to get approved by the owner and hey, I'm still waiting.
Gyaz I was able to use for a bit. I have to find my notes again, but I think it was almost TOO simplistic. I have coworkers that insist on wicked html email and sometimes even replying they went out horrendous. I'll have to look again, it's been a few weeks. I also found some inline images only showed up as red x's.
I think I just got frustrated with the lack of integration with the OS and decided with ML around the corner, maybe it was time to work with the OS a little better. I would be willing to try it again though.