IMAP credentials for popular providers
Server, port and the correct sign-in method for popular providers — and what to do when a connection cannot be established.
Server details at a glance
MailTransfer sets these values automatically in the wizard as soon as you select a provider. This overview helps if you would rather check them yourself.
IONOS
imap.ionos.de
Port 993 · SSL/TLS
Strato
imap.strato.de
Port 993 · SSL/TLS
All-Inkl
{domain}
Port 993 · SSL/TLS
With All-Inkl the username is usually an identifier such as w01abcde, not the e-mail address.
Hetzner
mail.your-server.de
Port 993 · SSL/TLS
one.com
imap.one.com
Port 993 · SSL/TLS
Gmail
imap.gmail.com
Port 993 · SSL/TLS
Google requires an app password (Account → Security → App passwords) with 2-step verification enabled. The "All Mail" folder is skipped, otherwise every message would arrive twice.
Microsoft 365
outlook.office365.com
Port 993 · SSL/TLS
Microsoft requires an app password, and IMAP must be enabled for the tenant — many organisations have turned it off. Ask your administrator if unsure.
Plesk / cPanel
mail.{domain}
Port 993 · SSL/TLS
Other provider
varies, see note
Port 993 · SSL/TLS
You will find server and port in your provider's setup guide or in your mail client's account settings.
App password instead of account password
Google and Microsoft no longer accept the normal account password once two-step verification is active. An app password is a separate password just for this purpose — revocable at any time, without changing your main password.
Google Account → Security → 2-Step Verification → App passwords
Microsoft 365
Microsoft account → Security settings → Advanced security options → App passwords
Find your server details yourself
The server and port are usually already in your existing e-mail program: open the account settings for the old mailbox there and look for “incoming mail server” or “IMAP”. Alternatively, your provider’s setup guide will help.
Two patterns come up most often:
imap.yourdomain.com mail.yourdomain.com
If your provider differs, its own help page will usually explain.
Common error messages
These messages appear during the connection test or the transfer. The right-hand column shows what to do in each case.
| Message | What to do |
|---|---|
| Username or password was not accepted. Gmail and Microsoft 365 require an app password. | Check the username and password for typos. For Gmail or Microsoft 365, use an app password instead of your normal account password (see above). |
| The mail server could not be reached. The address or port may be incorrect. | Check the server address and port in your e-mail program’s account settings or in your provider’s instructions. |
| The server’s security certificate could not be verified. | The server is probably using an incorrect, self-signed or expired certificate. If in doubt, ask your hosting provider for the correct server address. |
| The server could not be found in DNS. Is the address correct? | Check the spelling of the server address — a single missing or wrong character is enough to make it unfindable. |
| There is not enough storage space in the target mailbox. | Free up storage space in the target mailbox, or choose a larger plan with your provider before trying again. |
| The provider is currently limiting the number of simultaneous connections. Please try again later. | Wait a few minutes and start the check again — many providers throttle IMAP access from time to time; this is not an error on our end. |
Folders and special cases
Gmail labels are not real IMAP folders, and “All Mail” contains every message a second time. The folder is therefore deliberately left out — otherwise every message would arrive twice in the target mailbox.
Microsoft throttles IMAP access on its side when many requests arrive in quick succession. This slows the transfer down but does not stop it — MailTransfer simply waits out the throttling.
IMAP transmits folder names using a modified UTF-7 encoding. MailTransfer converts this automatically; accented and special characters arrive unchanged in the target mailbox.
These are pure structural folders with no messages of their own, marked by the server as “\Noselect” — for example a root folder that exists only to organise things. They are skipped, but their subfolders are transferred normally.