SMTP Error Codes: What Each One Means and How to Fix It
One table with the common SMTP error codes, what each means and its usual cause, plus a jump to the error section of your email provider.
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Also here: hand-checked directory and link lists, plain-English Basic guides, SEO and AI tool picks. Run by one webmaster since 2006.
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List health
Links last checked1,700sites working
7dead, parked or moved this month
0new sites added this month
534dead or bad sites deleted so far (7 this month)
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Hand-checked lists. Dead sites are removed by a link checker.
Get your site listed
Free DirectoriesGeneral web directories that still accept free submissions.148● workingInstant ApprovalDirectories that publish your listing right away.249● workingLocal DirectoriesPlaces to list a local business after Google Business Profile.530● workingPaid DirectoriesPaid directories with editorial review.182● workingPublish and share
Classified SitesFree classified sites for local ads and leads.63● workingArticle DirectoriesSites where you can still publish original articles.227● workingSocial BookmarkingBookmarking sites for discovery and visits.109● workingBlog CommentingBlogs with open comments — join real conversations.324● workingPopular free tools
No sign-up. The most used tools this month.
Website SEO CheckupNEWPaste a page address and get a score out of…PageRank CheckerNEWCheck the Open PageRank score (0 to 10) of u…Photo EditorNEWCrop, straighten, brighten and sharpen a pho…Image to WebPNEWTurn JPG and PNG images into smaller WebP fi…CSS MinifierNEWEnter a page URL to find every stylesheet an…Security Headers GeneratorNEWPick the security headers you need and copy…robots.txt GeneratorNEWBuild a robots.txt file for WordPress, Blogg…Domain Expiry CheckerNEWEnter one or more domains to read official r…
Beginner Guides
All 55 Basic articles →
Proton Mail SMTP Settings
The SMTP server, port and login for Proton Mail, how to make an SMTP token, who can use it, and why reading mail in apps needs Proton Mail Bridge.
Namecheap Private Email SMTP Settings
The SMTP, IMAP and POP settings for Namecheap Private Email, which password to use, and how to set it up in WordPress, email apps and phones.
SendGrid SMTP Settings
The SMTP server, ports and login for SendGrid, why the username is apikey, how sender identity works, and what common SendGrid errors mean.
Brevo SMTP Settings
The SMTP server, ports, login and SMTP key for Brevo, what to set up first, how to use it in WordPress, and what common Brevo errors mean.
SEO Blog
All 35 Blog articles →
Which rel Attribute Should Directory Links Use?
nofollow, sponsored and ugc in plain HTML, which one fits each kind of directory listing, and what a labelled link still does for the site in it.
Do URL Indexing Tools Improve SEO Results?
Indexing is not ranking. Here is what Google says about indexing tools, why some pages never stick, and what SEO results you can realistically expect.
Should I Use a Keyword Research Tool?
Free keyword tools cover most blogs and small sites. Here is what each type does, how free and paid tools differ, and a simple test for when paying makes sense.
Website Directory Submission: Step by Step
Editors reject most directory submissions for simple reasons. Prepare the right title, description, category and contact details, then follow these steps.
Website Loading Slow but Internet Fast? Here's Why
Fast internet, slow site? The bottleneck is usually the website: server response time, heavy images, too many scripts. How to find the real cause and fix it, without buying hype.
