I've used pmail on my personal computer for about 20 years. A few days ago it seemed like pmail auto- updated itself altho I didn't think that was possible. The inbox font looked different, etc. But I thought everything was working so I didn't worry about it.

Then I found out that distribution list emails I'd sent out had NO info in the From field - no name, no email address. So people thought the email was spam and deleted it without reading it! I tried to open the help interface via the Help menu but the Help stuff didn't appear on the screen.

I saw that the version I had was 4.73 so I went to the website and saw there is a more recent version. Tonight I installed 4.80 update thinking maybe that would solve these problems.

No, it did not. AND I sent a single email (not thru dist list) to one of my own email addresses, and there was no From info in that email, either!! Plus the outgoing emails were using sig text that I stopped using years ago.

I found a post on this forum about fixing the Help screen not showing up after 4.80 install, and that worked. But I still couldn't remember where the heck the info for the From field got entered in pmail.

I finally found the place to enter my name in Tools/Options/Basic Settings. And then found where to put my email address in Internet Mail Options/General. But sheesh! I spent hours trying to figure all this out. Why would an upgrade cause the help screen to be out of range of the monitor, remove my name and email address from From field settings, and use an old sig, but otherwise seem to function OK? (I sure hope everything else is OK.) POP and SMTP, mail folders and emails - all that was untouched.

FYI for your diagnostic purposes:
Windows 10 21H1
Windows Security has all features turned off because I installed the basic version of Bit Defender about a week ago. I did not notice any problems from that.

I really don't want to switch to any other email program, but it's very troubling to me that this seemed to happen without me changing anything while 4.73 was running.

Check what you have in these settings.
Tools/Options/Outgoing mail/sending
What does it have in default reply to??

Tools/Internet Options/General
What does it have for internet address??

Tools/Internet Options/Sending/ Click Edit.
Under General
is use alternate email checked? If so, what does it have in field.

Would check if those are correctly set, or if somehow they got corrupted?
That would be what I would check first.

I believe what happened is that one of the Pegasus Mail configuration files (likely PMAIL.INI since this would explain the different looking inbox) somehow got corrupted resulting in a reversion to default settings. Corruption can happen when something interrupts the writing of the configuration file (several are written to at every shutdown). This kind of corruption is rare but is not unheard of. Sometimes the cause can not be identified but a couple of known potential causes are:

1. Running Pegasus Mail as the same Pegasus Mail user simultaneously another instance of Pegasus Mail can also cause it.
2. Active scanning of the mailbox directory by an anti-malware product.

If you have a recent backup of your mailbox folder you can try restoring that version of PMAIL.INI. Do it with Pegasus Mail closed. Rename the current one first so that you can restore it should the one from the backup not work.

Also, if you are not aware of the bugs in v4.80 here is what you need to know:

1. The v4.80 spell checker is broken for user added words. Those words are supposed to be stored in USRDICT5.PMD but that file gets emptied each time the spell checker is invoked. Attempts to add words fail. The workaround is to set that file to read only before it gets emptied. If that has already happened then you can restore one from a backup and mark it read only. You won't be able to add any additional words but you will have the ones previously saved.

2. Bearhtml is causing crashes. A reproducible one is the use of a mouse scroll wheel while viewing HTML content. There have been reports of random ones as well. Although it is associated with Bearhtml, updating IERenderer will fix it.

3. There is a problem with the German version of IERenderer. Its resources don't load when the German version of Pegasus Mail is used. updating IERenderer will fix it.

Was just wonder if maybe some anti-virus or anti-malware or crazy program might have removed lines from the PMAIL.INI file thinking it was being a security issue having an email address in file?

Was wondering if the lines where intact in the PMAIL.INI or perhaps lines where there with no email addresses?

On my machine these are lines with email addresses in them.
cat PMAIL.INI| grep "@"
Alternative From: field for message = mikes@guam.net
Default reply-to address = mikes@guam.net
Internet E-mail Address = mikes@guam.net
Default reply-to address = msetzerii@gmail.com
Internet E-mail Address = msetzerii@gmail.com
Alternative From: field for message = mikes@guam.net

Also, some of the *.PND files also have email lines.

Don't see how Pegasus would do this, but could see some program thinking it was a good feature to have their program clean emails from *.INI files?.

Just a though?

When a PMAIL.INI file gets munged Pegasus Mail creates a new one with default values. Usually you must add back the SMTP and POP3 hosts as well as changing all other config settings that were not at default so I am surprised that a failure to send and receive was not mentioned in the original post.

I previously mentioned active scanning of the mailbox directory as a potential cause so wish to emphasize that Bit Defender should be configured to exclude it (Bit Defender uses the term "exception" ).