Some e-mail providers (Fastmail, Google, Proton) require an App Password/SMTP token for sending e-mail through their services. That app password/token relies on the base e-mail address but the provider allows a "from" address to be used. I suggest providing an optional "From" address that can be used to direct replies to an alias or other visible e-mail account.
Implemented Today: My E-Mail Address: name@somedomain.com
SMTP Password: *******
When the e-mail goes out it uses the "My E-Mail Address" as the "from" address. I propose: My E-Mail Address: name-gateway@somedomain.com
SMTP Login: name@somedomain.com
SMTP Password: ***** If the "SMTP Login is empty, use the My E-Mail address field. If SMTP Login is not empty, use that login. When sending the e-mail use the "My E-Mail address". The "my e-mail address" field could be renamed to "Reply to e-mail address" or "from e-mail address".
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The feature was developed and will be out in the upcoming version. which wont take long this time :)