WordPress SMTP Plugin — Asteris SMTP + Email Logs

Why does WordPress need an SMTP plugin? WordPress’s default wp_mail() function uses PHP’s mail() function, which sends email via your web server’s local mail transfer agent. On most hosting environments this is unreliable — emails get marked as spam, blocked by reputation filters, or simply not delivered. Password resets, form notifications, comment notifications, order confirmations, and every other site-generated email is at the mercy of the host’s mail config.

An SMTP plugin replaces wp_mail() with an authenticated connection to a real mail service (Gmail, Microsoft 365, SendGrid, Mailgun, Amazon SES, or any generic SMTP server). The mail is sent through a trusted provider with proper SPF/DKIM/DMARC alignment, which dramatically improves deliverability.

Does Asteris SMTP support Gmail and Microsoft 365 OAuth? Yes — both with full OAuth 2.0 (not legacy “less-secure apps”). In the free tier. Plus SendGrid, Mailgun, Amazon SES via native APIs (paid tier), and generic SMTP for any provider with host/port/auth credentials (free tier).

Does Asteris log emails? Yes. Basic email logs are in the free tier — recipient, subject, date, status. The paid tier adds full body capture (HTML + plain text), one-click resend, bulk resend, CSV export, configurable retention, and bounce/complaint webhooks.

The complete feature set

6 provider presets

Free tier:

• Generic SMTP — any host with host/port/username/password (e.g. SMTP2GO, Postmark, Mailtrap, your hosting provider’s SMTP, etc.)
• Gmail — OAuth 2.0 (the modern, secure path; works with personal and Workspace accounts)
• Microsoft 365 — OAuth 2.0 (modern auth for Microsoft 365 / Outlook / Hotmail Workspace)

Paid tier:

• SendGrid — native API integration (not SMTP relay — faster + better deliverability tracking)
• Mailgun — native API integration
• Amazon SES — native API integration (lowest cost at scale)

Basic email logs (free tier)

• Recipient, subject, date, delivery status (sent / failed / bounced)
• Error messages on failed sends (full SMTP / API error response)
• Search by recipient, subject, date range, status
• 30-day retention by default

Full email logs (paid tier)

• Full headers + full body (HTML + plain text) of every send
• Recipient list (To / Cc / Bcc, with redaction options for PII)
• Attachment list (filename + size; not the attachment binary, to keep DB small)
• Delivery status — sent / failed / bounced (where the provider returns it)
• Error messages on failed sends (full SMTP / API error response)
• Search by recipient, subject, date range, status
• Resend any logged email with one click
• Bulk resend — select multiple, resend all
• CSV export
• Configurable retention (default 30 days, extendable)

Security

• AES-256-CBC encryption at rest for all SMTP credentials (passwords, OAuth tokens, API keys)
• Field-level redaction via asteris_activity_log_redact_value filter — sensitive fields never enter the Activity Log
• OAuth tokens auto-refresh before expiry; no manual re-authorisation

Deliverability tools

• Test send — verify provider config without sending to a real user
• DNS check — verify SPF, DKIM, and DMARC alignment for your sending domain
• Deliverability alerts — email digest when failed-send threshold exceeded
• Bounce + complaint webhook (SendGrid / Mailgun / SES) — auto-suppress hard-bounce addresses

Retention cron

• Auto-purge email logs older than the retention threshold
• Per-provider exclusions (e.g. keep transactional sends 90 days, marketing sends 30 days)
• Runs on standard WP-Cron or external cron trigger

Free version

Asteris for WordPress Free on WordPress.org includes a lite SMTP with generic SMTP support only — no OAuth, no native APIs, no full email logs. For OAuth + full logs, you need a paid Asteris tier ($149/yr Starter).

Frequently asked questions

Why does WordPress need an SMTP plugin? WordPress’s default wp_mail() uses PHP’s mail() function, which is unreliable on most hosting. Password resets, form notifications, and every site-generated email get spam-filtered or blocked. An SMTP plugin routes mail through an authenticated provider (Gmail, SendGrid, etc.) for reliable delivery.

Does Asteris support Gmail OAuth for SMTP? Yes — full OAuth 2.0 for Gmail (personal and Google Workspace). Setup takes about 60 seconds via a popup OAuth dance; no app-password workaround required.

Does Asteris support Microsoft 365 OAuth? Yes — modern auth (OAuth 2.0) for Microsoft 365 / Outlook / Office 365 / Hotmail Workspace accounts.

Can I keep full email logs? Yes, in the paid tier — full headers + body (HTML + plain text), recipient list, delivery status, resend, bulk resend, CSV export. WP Mail SMTP gates equivalent logging to its Pro+ tiers.

What is the best WordPress SMTP plugin? For free + reliable: Fluent SMTP (free, well-built). For paid + bundled: Asteris SMTP (in Asteris Starter at $149/yr, with 10 other modules). For paid + SMTP-only: WP Mail SMTP Pro ($49-$199/yr depending on tier).

Are credentials secure? Yes — AES-256-CBC encryption at rest for all SMTP credentials, OAuth tokens, and API keys. Tokens auto-refresh; passwords never appear in logs.

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