Support » Plugin: Post SMTP Mailer/Email Log » Error: Invalid “To” e-mail address

  • We are using the latest Post SMTP version (2.0.15). When we try to send a mail at a specific domain ( we get:

    > Invalid “To” e-mail address “”

    I even tried to type the email char by char when trying the ‘re-send’ option but I get the same.

    It works on my personal mail and every other domain I tried.

    Here’s the debug test:

    Mailer: postsmtp
    cURL Version: 7.52.1
    OpenSSL Version: OpenSSL/1.0.2u
    OS: Linux shop 4.9.0-8-amd64 #1 SMP Debian 4.9.130-2 (2018-10-27) x86_64
    PHP: Linux 7.0.33-0+deb9u8 en_US.UTF-8
    PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=No, zlib_encode=Yes
    WordPress: 4.9.15 en_US UTF-8
    WordPress Theme: Make
    WordPress Plugins: Query Monitor, Gravity Forms, PW Advanced Woo Reporting, Advanced WPLink, AffiliateWP, Archived Post Status, Booster Plus for WooCommerce, Broken Link Checker, Change Prices with Time for WooCommerce, Clean WP Admin Menu, Admin Columns, coinbase-woocommerce, Custom Sidebars, Enable Media Replace, Products & Order Export for WooCommerce, Finale - WooCommerce Sales Countdown Timer & Discount Plugin Lite, GloBee, Insert Headers and Footers, Purser - LDH & WooCommerce integration plugin, Make Plus, Order / Coupon / Subscription Export Import Plugin for WooCommerce (BASIC), PHP Compatibility Checker, Post SMTP, Post State Tags, Redirection, RPS Include Content, Simple Custom CSS, Simple History, Simple LDAP Login, Splitit, TablePress Extension: Larger Edit Input Fields, TablePress Extension: Responsive Tables, TablePress, Tag Selector, TaxJar - Sales Tax Automation for WooCommerce, Ultimate Category Excluder, WooCommerce Edit Order Numbers, UpdraftPlus - Backup/Restore, User Role Editor, Username Changer, WC Simple Product Badge, WooCommerce Easy Duplicate Product, Advanced Order Export For WooCommerce, WooCommerce Advanced Free Shipping, WooCommerce Extended Coupon Features FREE, WooCommerce Cart URL, WooCommerce Composite Products, WooCommerce Conditional Shipping and Payments, WooCommerce Email Test, WooCommerce Stripe Gateway, Teams for WooCommerce Memberships, WooCommerce Memberships, WooCommerce Custom Payment Gateway, WooCommerce Product Bundles, WooCommerce Product SKU Generator, WooCommerce Redirect Thank You, WooCommerce - ShipStation Integration, WooCommerce Subscriptions, WooCommerce TM Extra Product Options, Woocommerce Ultimate Reports, WooCommerce, WP Dashboard Notes, WP Full Stripe Free, WP Maintenance Mode, WP-Matomo, WP Super Cache
    WordPress wp_mail Owner: /var/www/html/
    WordPress wp_mail Filter(s): wp_staticize_emoji_for_email, PostsmtpMailer->get_mail_args
    WordPress phpmailer_init Action(s): PostsmtpMailer->phpmailer_smtp_init
    Postman: 2.0.15
    Postman Sender Domain (Envelope|Message): |
    Postman Prevent Message Sender Override (Email|Name): No | No
    Postman Active Transport: SMTP (smtp:tls:login://
    Postman Active Transport Status (Ready|Connected): Yes | Yes
    Postman Deliveries (Success|Fail): 456455 | 3914
Viewing 4 replies - 1 through 4 (of 4 total)
  • supaiku


    I also have this issue on a WPEngine hosted site, sending with Google Suite.

    It seems to impact all .llc domains.

    Any updates on this?

    Guess this was pretty straightforward, just add llc to the list of valid domains… Works 🙂

    You can do this on your own webserver by changing the line noted in this commit:

    Mods like this are overwritten when a new update is released, but hopefully the fix will be committed before the next update.

    It’d be swell if this fix could get merged so we don’t have to keep manually patching it, thank you!

Viewing 4 replies - 1 through 4 (of 4 total)
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