In Thunderbird, I can directly edit the "From" field to whatever value I want when I send the email.
I can make it a random value such as "abc123456789@example.com" and it will happily try to send it. The email address can also be from a domain I don't even own.
From the Gmail, docs, I have to manually go to settings, enroll the additional email address, then manually have to select the "From" address from the dropdown menu. I cannot put an arbitrary email address (including arbitrary domain). This will have to be done each time I want to have a different from header which means if I want to have a randomly generated email used as the "From" address for every one of my emails, it's not going to be easy in the Gmail interface.
Actually quite often. I'm very surprised users do not use unique email addresses when contacting different companies or vendors to protect against spam if one of your email addresses gets leaked after the company is hacked.
For example, I would use email address A for company A, B for company B and so forth. If company A ever gets hacked, I can just block any emails going to email A and not worry about playing whack-a-mole with the 100s of email addresses that spammers will use.
I can also use the email addresses as a way to auto filter or apply inbox rules.
I'm very surprised users only use 1 email address at a time especially if your email gets leaked once to spammers, you have to start dealing of spam or hoping your email solution has very very good anti-spam measures.
For me, this is just a normal usage of an email client.
I don't do it daily, but it's still often enough usage for me that having to set each one up individually would grind my gears. My own domains setup with catchalls and many custom name@ across services. I might be unusual though!
Not that unusual; I've been doing the same since the 1990s.
For each organisation, project or person I interact with over email I issue a unique ${RANDOM}.${ORG}@mydomain.org across many separate domains.
Combined with procmail rules on my email server I can more easily:
1. efficiently filter and file emails into per-org, per-topic or per-project sub-directories
2. have all IMAP4 clients see the same view since filtering/filing is done server-side
3. block any addresses that receive spam without accidentally binning other email
4. know for certain there has been some kind of breach if emails arrive from another source
5. have some clients subscribed and sync-ing to only a (small) sub-set of IMAP4 folders
6. find emails related to specific orgs, projects, or people
I use Qmail's Maildir format (one file per email) on both server and Thunderbird which makes even manual 'grepping' for obscure or complex search parameters an easily scriptable operation.
I have a simple script accessible via SSH or web that adds the new entry to postfix's virtual table so unknown addresses are rejected - avoids needing to operate a catch-all policy and filter after reception since the SMTP daemon refuses delivery as soon as it sees the RCPT TO:
On the Postfix side using postgrey for grey-listing of unknown SMTP clients cuts almost all spam as well - in fact today I was surprised to see (for the first time in years) Thunderbird marking a project mail-list email as possible spam. I cannot recall the last time Thunderbird did that which I think shows how effective grey-listing on the mail server can be combined with other postfix filtering like reverse MX, SPF, DMARC, etc.
