Possible Solutions for Server Error 503
- Apostrophes – remove any apostrophes (single quotes) or other non-alphabetic characters from your email account name(s).
- Outlook PST files – sometimes the 503 error will occur if you have a corrupt Outlook PST (mail archive) file. Try deleting the file and recreating your archive file.
- VPN – if your system is trying to connect via a VPN network while you’re sending email, you may get this error. Try disconnecting the VPN before sending/ receiving mail.
- Full mailbox – make sure the mailbox of the affected account is not full or has met/ exceeded its quota. You can uncheck the following option to make sure a copy of all your emails is not being left on the server (note that since the email will be downloaded to your PC after this setting change, you won’t be able to access your emails from another location if you do this). In Outlook, browse to Tools > Account Setting > More Settings > Advanced > Uncheck “leave a copy of this message on the server.”
- SMTP port – use port 26 (instead of the default 25) for outgoing mail.
- Server authentication – setup your outgoing mail to use outgoing server authentication (sends mail by logging in with your email address and password).
In Outlook, browse to Tools > Account Settings > More Settings > Advanced and change the outgoing server to ‘Auto.’ Next, browse back to More settings > Outgoing server and check the “My outgoing server uses the same authentication as my incoming server” box. If you select to have Outlook “remember your password” you won’t have to type it in every time you send an email.
- Sender matching – make sure you’re sending from the same email address that the recipient sees your email coming in as (ie. don’t make the “from” field differ from the email address used in your outgoing mail settings).
If none of these approaches work, or you need more detail on a particular step, please read the rest of this guide for some additional suggestions.
503 Valid RCPT Command Must Precede DATA
We recently got this RCPT to command error when trying to send an email in Outlook. The culprit? Apparently, this occurs when a server is expecting to receive mail before sending. This is usually results from server authentication priorities (for example, you attempt to send mail before your “spam filter” has finished its receiving process.)
Solutions to Resolve the 503 RCPT Error
- Pop before SMTP — Run a check for new messages (F9 key in Outlook) before sending your message and restart and rerun your spam filter application. Your IP address is entered in a relay hosts file, allowing email to be sent from your address for up to half an hour.
- If the problem still persists check “my server requires authentication” to authenticate automatically. With this setting, you can bypass the check above and send mail without having to “pop” your mailbox first. You can also try changing the outgoing port from 25 to 26, since some ISP’s block this port.
- Several of our readers have pointed out that it may help to remove apostrophes from your email account names (and ask senders to remove them if you’re having trouble receiving emails from them).
- If you’re on a VPN, try disconnecting from the VPN prior to using your mail program.
- Your mailbox may be full – try clearing out messages or asking your mail service provider to increase your mailbox limits.
- If you are using multiple mailboxes, make sure these fixes/settings are applied to each one of them, especially the “default” one.
- Finally, if using a mail screening utility such as Mail Washer, you may want to disable the “automatically check at intervals” setting and check mail manually. If the system checks mail while you are sending you may get this error.
Still Having Trouble?
If none of the above work we recommend contacting our support team.
