Reply from the address that was written to.
info@, contact@, and your first name land in one inbox. A domain of your own, an alias for orders, an address per project. In Postfach every account knows the addresses it may send from, From offers them all, and a reply goes out from the address the message was sent to. Whoever writes to you at contact@ gets the answer from contact@.

Every address of an account.
In Settings › Accounts, every account has a section Other Sender Addresses under its servers. There you enter the aliases and addresses your provider lets you send from with this account, one per row, with a name of its own if you like. Without one, it goes out with the account's name.
Whether an address may send is your mail server's decision, not Postfach's. With most providers you set up an alias or a domain of your own there first, and then add it here.
- Up to fifty addresses per account, with Add Address and a minus to take one out
- A row that is no email address says so, and Save waits until it is right
- The account's own address and repeats drop out by themselves
- The settings file takes the addresses to your other devices
In the From field.
As you write, From lists the addresses of all your accounts, each account's own address first and its others under it. Pick another address of the same account and only the From line changes: the signature, the server, the format, and the Sent folder stay the account's. Pick an address of another account and the whole account changes.
- The picked address stands in the message's header and is the sender your server sees
- Collapsed, the Cc/Bcc, From row shows the address the message goes out from
- A draft you finish later comes back with the address you saved it with
The reply knows who was written to.
When you answer a message, Postfach looks among its recipients for the first of the account's addresses, in To first, then in Cc, and replies from it. Your correspondent sees the address they wrote to, and the conversation stays on it. Where the message names none of your addresses, as a blind copy or by way of a mailing list, the account replies with its own.
- For replies, Reply All, replies with a template, and forwards
- You can still change the address in From at any time
- Reply All puts none of your own addresses back among the recipients
Your addresses stay yours.
Everywhere in Postfach, another sender address counts as the account's own address does. Mail to it is addressed to you and no blind copy, also mail that was there before you added the address. And your own mail is caught by no rule meant for strangers.
- Junk rules and blocked senders spare mail from your addresses
- Postfach Contacts does not list your own addresses as contacts
- Trust Sender, Add to My People, and Block Sender… are not offered for mail from your addresses
- An alert for new messages does not count a reply you filed in its folder yourself
When the login is not the address.
On a mail server of one's own and at many smaller providers, you sign in with a mailbox id or a username, not with the address. Add Account has a Username field for it, after the password. Left empty, Postfach signs in with the address, as before. Filled in, it signs in with the username and sends as the email address.
- In Settings › Accounts, Email and Username are two fields of their own, both open to change
- Messages always go out from the email address or another sender address, never from the login
When the server says no.
Where your mail server does not let an account send from an address, the Outbox says just that, “The server doesn't let this account send from this address”, and what to check in Settings › Accounts. It does not blame a recipient's address. The server's own words are under Server Message.
- After a new username, Send Again helps
- A message keeps the address it was written with: after a new sender address, delete it and write it again
And where the reply is filed.
A reply's copy is kept in Sent as a rule. Under Filing Replies in Settings › Accounts, an account can put it into the folder of the message it answers instead, the inbox too. A project's or a customer's folder then holds both sides of the conversation, in every mail program, in webmail as on another device, and whoever moves or archives the conversation takes the replies along.
- Where the conversation lies in several folders, With several folders chooses between Folder on screen and Folder of the answered message
- File forwards too and Also file in Sent, as you wish
- Replies to messages in Sent, Drafts, Trash, or Junk go to Sent, and so do replies from another account
- Where the folder is gone by the time the message goes, the copy goes to Sent
- Without the copy in Sent, a filed reply is missing from Sent, All Sent, and smart folders of sent mail
Good to know.
The account's signatures
Another address has no signature of its own: it uses its account's signatures, and a change of address leaves the chosen one in place.
Shared from the account
Junk rules and templates you send to your other devices by email go out from the account's address and are taken from it alone, never from an alias.
Nothing in between
Postfach sends straight through your account's outgoing mail server. No server of ours sees from which address you write to whom.