Your old address, in your new inbox
Connect a t-online, GMX, WEB.DE, or other email account to your PostStack mailbox and read and answer it in the same place. Replies go out from the old address, through its own provider, so nothing changes for the people who write to you.
anna@holzwerk-berg.de
PostStack
holzwerk.berg@t-online.de
t-online.de
anna.berg@gmx.de
GMX
Add another email account
Email address
Password for t-online.de
One inbox, every address
Switch between your new address and up to five older ones from the account menu. Read, reply, archive, and delete as if they were one mailbox.
Replies come from the right address
An answer to a message sent to your GMX address goes out from GMX, through GMX’s own servers, and lands in GMX’s Sent folder — exactly as if you had sent it there.
Nothing copied, password locked away
The other account’s mail stays with its provider and is fetched only while you look at it. Its password is stored encrypted, is never shown again, and is deleted the moment you disconnect.
Get started
- 1
Open the account menu
In webmail, click your address in the top corner and choose “Add another email account”.
- 2
Type the address and its password
PostStack finds the server settings on its own and tells you which password the provider expects.
- 3
Switch between them
The connected account appears in the same menu. Pick it to read its inbox; pick your own to go back.
Use cases
Moving a business to its own domain
Customers have your old t-online address on invoices, vans, and business cards. Keep answering it while you move to info@your-domain, with both inboxes a click apart.
Leaving Gmail’s “check mail from other accounts”
Gmail on the web is dropping the option to fetch mail from other accounts. PostStack reads those accounts directly, whenever you open them, instead of copying mail between providers.
A private address next to a work one
Keep a personal WEB.DE or Posteo address visible beside your company mailbox without a second app or a second browser tab.
Retiring an address gradually
Read and answer the old account until the mail stops arriving, then disconnect it. Its mail stays with the old provider for as long as you keep that account.
How it works
A connected account is read over IMAP and sent over SMTP, the same standard protocols a desktop mail program uses, from PostStack’s servers in Helsinki. Settings are built in for t-online.de, GMX, WEB.DE, Yahoo, iCloud, mailbox.org, Posteo, IONOS, and STRATO; for any other address PostStack looks the provider up in Mozilla’s public mail-settings database and in the domain’s MX records, and the server names and ports can always be entered by hand.
Many providers refuse the password you use on their website and expect a separate one for mail programs — t-online calls it the “Passwort für E-Mail-Programme”, Yahoo and iCloud call it an app password, and GMX and WEB.DE want IMAP access switched on first — so the form shows the right instruction for your provider before you type anything.
No copy of the other account’s mail is kept at PostStack: folders, messages, and attachments are fetched live from the provider while you are looking at them, and read, flagged, archived, and deleted states are written straight back there. Sending uses the provider’s own outgoing server with your credentials, and a copy is saved in that account’s Sent folder, so replies pass the provider’s SPF and DMARC checks and look exactly like mail you wrote there.
The password is encrypted before it is stored, is never returned to the browser, and is removed together with the connection. If the provider starts refusing it — because you changed it, for example — PostStack stops trying and asks you for the new one. Only the mailbox that connected an account can open it; the PostStack dashboard, API keys, and other mailboxes on the same domain cannot. Outlook.com, Hotmail, and Gmail accounts cannot be connected yet, because Microsoft and Google no longer accept a password from services like this one.
Every parameter, limit, and example is in the documentation.
Frequently asked questions
Which providers work?
t-online.de, GMX, WEB.DE, Yahoo, iCloud, mailbox.org, Posteo, IONOS, and STRATO are set up for you. Most other providers work too — PostStack finds their settings automatically, or you enter the server names yourself.
Why does t-online say my password is wrong?
t-online accepts only the “Passwort für E-Mail-Programme” from mail programs, not the password for its website. Create one in the Telekom Kundencenter under E-Mail → E-Mail-Passwort and use that.
Can I connect Gmail or Outlook.com?
Not yet. Google and Microsoft require their own sign-in for services like this one instead of a password. PostStack says so as soon as you type the address, rather than asking for a password that cannot work.
Does PostStack store my old mail?
No. Mail from a connected account is fetched from its provider while you view it and is not kept. Only the account’s address, server settings, and encrypted password are stored.
Will people see a different sender?
No. Mail you send as the connected address goes out through that provider’s own servers, exactly as if you had written it in their webmail.
Does it cost extra?
No. Up to five connected accounts are included with every PostStack mailbox (€1 per month on any paid plan).