How to Fix “503 valid RCPT Command Must Precede DATA” Error

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Help meFor those that are tearing their hair out when getting the “503 valid RCPT command must precede DATA” error (we’ll refer to it as simply the “503 error” going forwards) when trying to send email, here are some common solutions that will hopefully get you back up and running. If these don’t work, or you need more detail on any of these steps, please read the rest of this article, and its comments, for some more in-depth solutions.

Possible Solutions for Server Error 503

  • Apostrophes – remove any apostrophes (single quotes) or other non-alphabetic characters from your email account name(s).
  • 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).
  • Outlook PST files – sometimes the 503 error will occur if you have a corrupt Outlook PST (mail archive) file. Try repairing the file.

If none of these approaches work, or you need more detail on a particular step, please read the rest of this article 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 your hosting provider. Your mail services account needs to be set up properly (associated with the right username, etc.). We encountered this exact problem when switching hosts once – the mail server configuration got goofed up, and none of the above solutions worked. In the interim (until settings are fixed by your hosting provider) you can adjust your outgoing mail server to reflect that which your ISP uses, which should let you send mail again through your local client (Outlook, but not from the server (Webmail), until the problem is fixed.

As mentioned previously, to keep your mail system running smoothly, and to help you get rid of various email related errors, including the 503 valid RCPT error, we recommend installing a solid anti-spam solution. Anti-spam software is affordable, but your email and privacy are priceless. Don’t let the spammers get the best of you. And be sure to check out more troubleshooting tips.

Have you had this issue before?

Alex bring a series of in-depth articles on search marketing and content management systems as well as troubleshooting tips to We Rock Your Web's collection. He is an avid tennis player, nature enthusiast, and hiker, and enjoys spending time with his wife, friends, and dogs, Bella and Lily.

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83 Comments on "How to Fix “503 valid RCPT Command Must Precede DATA” Error"

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Carla
I just found out that my new web host’s servers don’t work with the combination of Windows 7 and Outlook 2010. I was given the choice to move to older servers but I opted not to do that. Instead, I’m going to break away from Outlook entirely and use Thunderbird. It’s free, super easy to use because it does the settings for you, and was recommended by a tech at the hosting company who has used it for over a decade.

Mozilla actually just launched the new Thunderbird.net site yesterday, which indicates their commitment to supporting it in the future.

Tatz
This was awesome instructions are great didnt take me more than 5minutes to solve the problem thank you so much !!!
Kimberly Alt
Glad we could help!
Irene
Found another cause of this problem. I had an attachment with rounded brackets in the file name. A word docx. Thanks for the help, it sort of took me in the right direction with the note about the apostrophes…
Harlan
“Use same settings as my incoming mail server” solved my problem
What is a 503 error? I don’t understand why there is a number associated with it, are there other 503 errors that are not related to this “valid RCPT command must precede data”
Jeff Butler
503 errors basically mean that the server of the web site you are trying to connect to is not available. So to answer your question specifically, yes there are many more 503 errors than just this specific one.
Lutaaya Gad
it really worked for me. thank you very much i.e server authentication
Wellington
Empty your email box, this solved my problem.
Gary
Removing non-alpha characters from my account name resolved the 503 issue. Thanks, Alex!
Andrzej Cojg
It is also worth noting that Outlook might have some difficulties while sending your message if your password consists of certain special symbols. In my workplace, using capital, small letters, numbers and symbols is a must for overblown security reasons. Reset your password to something less challenging and try again.

Side note: This problem could be related to your system language and coding (unicode, ansii, utf-8).

Irshad
Open Outlook click on Tools(2007) / File(2010) > Account Settings > Highlight the email account > Change > More settings > Outgoing server > Check the box ‘My outgoing server (SMTP) requires authentication’ > Verify that the circle-box ‘Use same settings as my incoming mail server’ is selected.
Carina De Almeida
Thanks Alex – port 26 did the trick!
Skewiff
I suddenly got this error message yesterday after years of doing nothing different! The server authentication (email address / password) was duly added and now it works – go figure!
Boba Fett
Boom! Port setting worked like a charm! Thanks.
Hussein Aladin
This helped a lot. Changed the server authentication to “auto” and now I am able to send outgoing mails. Thanks!!
Kimberly Alt
Glad this solution worked for you! Thanks for letting us know about your success!
Dmitro
I’m trying to set up my website email through just host and getting a 503 error when receiving emails. When I use a gmail account to send to my domain address email, I receive “503 This mail server requires authentication when attempting to send to a non-local e-mail address”. I tried looking everywhere and no matter what I do I can’t receive emails. Any help would be appreciated! Thank you.
Kimberly Alt
Is there any more information you can give us about your problem?
Andy
Great help…one of the suggestions worked! Thank you.
Kimberly Alt
You’re welcome! Glad we could help!
h82bL8
No help – bunch of technical jargon.
Kimberly Alt
Is there a question you have that we can help you with? If you’d like, you can explain your problem in detail and we may be able to explain it in another way to solve your problem.
Justin
Got it! Server auth and/or SMTP port change did the trick!
syed
Hi, I have checked with authentication of SMTP and I have changed the SMTP port also from 25 to 26 then also i cant able to send or receive any emails. Please help me out from this issue.

Madhavan R
Hi. As you had advised i had repaired the PST file for four hours (10 GB) and then found the same error occurring again, i deleted and re-configured the email id in the Microsoft Outlook that simply solved the error. Thought authentication – we use authentication mode for our outlook. Any ways, thanks a lot for your post and support!

Changing the port to 26 and it worked. Thank you!

Jeremiah
This worked for me!

Server authentication – setup your outgoing mail to use outgoing server authentication (sends mail by logging in with your email address and password).

Riqt
After testing all the above and nothing solved it. It turns out that our ISP (Telepacific) was blacklisting our domain/server and they said that a pc at our office was probably sending a lot of spam. We checked and it turns out that all the antivirus were working, active and updated, so they took us OFF the blacklist and the problem was solved.

Christiane
My outlook gave this error message, so I followed the steps above, changed to secure authentication and so on, it got worse, so I unchecked the authentication again and now it’s working just fine.

Does that equal beating the system over the head and then it wants to work?

I don’t get it, but something helped.

thanks.

vicki
Changing SMTP port – use port 26 (instead of the default 25) for outgoing mail.

& Server authentication worked for me.

Many thanks!

Kimberly Alt
Glad to hear it worked for you Vicki! Thanks for reading and commenting.
-Kimberly
I just changed the port and it worked for me. Thanks!

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